Health Library

The Health Library is a collection of health and wellness resources created for learning and accessibility. Select a topic below for related health information or search for a topic in the search bar for more information on other medical conditions.

Pathology

  • Helicobacter pylori tests are used to detect a Helicobacter pylori ( H. pylori) infection in the stomach and upper part of the small intestine ( duodenum). H. pylori can cause peptic ulcers. But most people with H. pylori in their digestive systems do not develop ulcers. Four tests are used to detect H. pylori...

  • Rapid sputum tests are used to diagnose tuberculosis (TB) when other tests show that a person probably has TB. Rapid sputum tests are also called nucleic acid amplification tests (NAATs). One of the best ways to diagnose TB is through a sputum...

  • If you check your blood pressure, you may wonder when an abnormal reading means you should call your doctor. This information can help you understand what your blood pressure numbers mean and when you need to call for help. What do blood pressure numbers mean? Your blood pressure consists of two numbers...

  • Find out which types of medicines require a regular blood test and why.

  • Cell-free fetal DNA is a screening test to look for certain birth defects in a fetus. It's done to find birth defects caused by an abnormal number of chromosomes. It also can reveal the sex and blood type of the fetus. This is a blood test for the mother. The test can be done as early as 10 weeks in the pregnancy. If...

  • A medicine blood level test measures how much of your medicine is in your blood. Your doctor checks it to make sure that you are taking a safe and effective dose. This testing is also called therapeutic drug monitoring.

  • Blood and urine are often tested to find the cause of health problems. But other body fluids also can be tested. Most of these fluids help organs and joints—and the membranes around them—move smoothly. Sometimes a health problem can cause too much...

  • At-home genetic tests check the DNA of your cells. These tests can find changes in your genes that increase your risk for certain health problems. You don't need a prescription from your doctor and you don't need to involve your health insurance...

  • Learn what to expect when your child gets a blood test.

  • Learn what a strep test is and how it's done.

  • Learn about urine tests for children and how they're done.

  • Learn what to expect when you have a blood test.

  • A COVID-19 viral test is a way to find out if you have COVID-19. The test looks for the virus in your breathing passages. There are different types of viral tests. One type looks for genetic material from the virus. This is usually called polymerase chain reaction (PCR). Another type looks for proteins on the...

  • An antibody test looks for antibodies in the blood. These are proteins that your immune system makes, usually after you're exposed to germs like viruses or bacteria or after you get a vaccine. Antibodies work to fight illness. A COVID-19 antibody test looks for antibodies to SARS-CoV-2, the virus that causes...

  • What is the first-trimester screening for birth defects? Near the end of the first 3 months of pregnancy (first trimester), a woman can have two types of tests to show the chance that her baby has a birth defect. When the results are combined, these tests are known as the first-trimester screening. They also may be...

  • Talk to your doctor about when a cholesterol test is right for you. Doctors use different guidelines to decide when a person should have a cholesterol test. Your doctor might suggest a test based on your age or your risk factors for heart disease....

  • An antibiotic sensitivity (or susceptibility) test is done to help choose the antibiotic that will be most effective against the specific types of bacteria or fungus infecting an individual person. Some types of bacteria or fungus are resistant to...

  • Guides through the decision to be screened for sexually transmitted infections. Explains STIs and discusses causes and lifestyles that put you at higher risk for getting infected. Covers benefits and risks of testing. Includes an interactive tool to help you decide.

  • Guides through the decision to be screened for an HIV infection. Explains HIV and discusses causes and lifestyles that put you at higher risk for getting infected. Covers benefits and risks. Includes an interactive tool to help you make your decision.

  • A d-dimer test is a blood test that measures a substance that is released when a blood clot breaks up. Doctors order the d-dimer test, along with other lab tests and imaging scans, to help check for blood-clotting problems. A d-dimer test can also be used to check how well a treatment is working.

  • Learn how insulin works and why diabetes causes high blood sugar.

  • Learn about the A1c test and how to make a plan to meet your safe target blood sugar level.

  • If you've found out that you have a BRCA gene change, you may be feeling pretty overwhelmed. But when it comes to cancer, knowledge is power. Now that you know you are BRCA-positive, you can take steps to reduce your risk of breast and ovarian cancer. Thinking about cancer risk Experts know that women who are...

  • This test measures the amount of prealbumin in the blood. Prealbumin is a protein that is made in the liver and released in the blood. It helps carry certain hormones that regulate the way the body uses energy and other substances through the blood. When prealbumin levels are lower than normal, it may be a sign of a...

  • Learn why getting a chlamydia test is important.

  • Learn why getting a pap test is important.

  • A vitamin D test measures the amount of vitamin D in the blood. Your body needs vitamin D to absorb calcium. Calcium keeps your bones and muscles healthy and strong. If your muscles don't get enough calcium, they can cramp, hurt, or feel weak. You may have long-term (chronic) muscle aches and pains. If you don't get...

  • DHEA-S (dehydroepiandrosterone sulfate) is a male hormone (androgen) that is made in the adrenal glands. The body turns it into testosterone. A test for DHEA-S checks the level of this hormone in the blood. Testosterone affects sexual features and development. In men, it is made in large amounts by the testicles. In...

  • Learn what happens during a complete blood count test and why you would need one.

  • Learn what is checked during a cholesterol test, why you might need one, and what the results may mean.

  • Learn what a thyroid blood test checks for, why you may need one, and what the results mean.

  • Learn what happens during a urine test, why it's done, and what it shows.

  • Learn what is checked during an HIV test, who might need one, and what the results may mean.

  • Doctors use the KOH preparation test to find out if you have a fungal infection. This kind of infection can happen in various parts of the body, such as the skin, nails, mouth, or vagina. KOH is the abbreviation for potassium hydroxide, the solution that is used in the test.

  • A nicotine test measures the level of nicotine—or the chemicals it produces—in your body. It's usually done by testing a sample of your blood or urine. The test is used to see if you smoke or use other forms of tobacco. All forms of tobacco have...

  • A tumor marker is a substance released by cancer cells or by normal cells when cancer is in the body. Tumor markers can be hormones, proteins, enzymes, or other substances. Some conditions that are benign (not cancer) also release tumor markers....

  • A medicine blood level test measures how much of your medicine is in your blood. Your doctor checks it to make sure that you are taking a safe and effective dose. This testing is also called therapeutic drug monitoring. This information is about medicines that are not used to control seizures. To learn about testing...

  • Myoglobin is a protein found in heart tissue and other muscles. It is released into the blood after damage to the heart or other muscles. Damage can occur from a serious event such as a heart attack or a burn. Myoglobin can be checked with a blood test or a urine test. Levels in the blood will increase within about 3...

  • The high-sensitivity C-reactive protein (hs-CRP) test is a blood test that finds lower levels of C-reactive protein (CRP). This protein measures general levels of inflammation in your body. The hs-CRP can be used to find the risk for heart disease and stroke in people who don't already have heart disease. The hs-CRP...

  • Clostridium difficile ( C. difficile) are bacteria that live in your large intestine, or colon, all the time. They usually don't cause problems. But sometimes, something causes the bacteria to grow. When there are too many of them, they release harmful substances called toxins. When the toxins are released, the...

  • Celiac disease is a problem that happens when gluten in food causes your immune system to attack the lining of your small intestine. As part of this mistaken attack, your immune system creates certain proteins called antibodies. If your doctor thinks you may have celiac disease, he or she will order a simple blood...

  • Tests for autoimmune diseases measure the amount of certain antibodies in your blood. Your body makes antibodies to attack and destroy substances such as bacteria and viruses. But in autoimmune diseases, the antibodies attack and destroy your body's tissues. This can lead to diseases such as rheumatoid arthritis...

  • A creatine kinase (CK) test checks the level of the enzyme creatine kinase, which is found in heart tissue and skeletal muscles. This enzyme also can be found in smaller amounts in the brain. A blood test to check the level of CK can show if there has been damage to the heart, skeletal muscles, brain, and sometimes...

  • Thyroid antibody tests measure the levels of antibodies that can destroy thyroid tissue or make the cells produce thyroid hormones. They are blood tests. Antibodies that destroy thyroid tissue can lead to hypothyroidism (underactive thyroid). Antibodies that make the cells produce thyroid hormone can lead to...

  • Guides through the decision to have colposcopy if a Pap test shows minor cell changes. Covers other choices such as watchful waiting and HPV testing. Includes interactive tool to help you make your decision.

  • Pregnancy does not seem to increase the progression of abnormal cervical cell changes. The presence of abnormal cervical cell changes or HPV does not affect the outcome of the pregnancy. Close monitoring is needed so that you and your health...

  • Discusses stool analysis, a test used to look for bacteria, parasites, or blood in the digestive tract. Covers why and how it is done. Looks at risks. Covers normal and abnormal results.

  • Hair analysis can be used to check if people are blood relatives. Forensic hair analysis can be done to help identify a criminal by evaluating hair structure and DNA from cells attached to the root of the hair. Hair samples are tested with specific chemicals and looked at under a microscope. Hair analysis can also be...

  • A breath alcohol test is an estimate of your blood alcohol concentration (BAC). The test measures the amount of alcohol in the air that you breathe out (exhale). You can measure your own breath alcohol level with a simple handheld device. If the device is calibrated and used according to the manufacturer's directions...

  • Guides you through choosing a test to check for colorectal cancer. Looks at symptoms of colorectal cancer. Covers stool tests, sigmoidoscopy, colonoscopy, and virtual colonoscopy. Includes interactive tool to help you make your decision.

  • Discusses blood urea nitrogen (BUN) test. Covers why and how it is done. Includes how to prepare for the test. Covers risks. Explains results of the test. Covers what affects results.

  • Guides through decision to have a PSA test to check for prostate cancer. Includes what PSA results tell you and what they do not. Covers benefits and risks. Includes an interactive tool to help you decide.

  • Guides you through the decision to have screening tests to look for Down syndrome and birth defects. Discusses what the tests look for. Covers benefits and risks. Includes interactive tool to help you make your decision.

  • The uric acid urine test measures the amount of uric acid in a sample of urine collected over 24 hours. Uric acid is made from the natural breakdown of your body's cells. It's also made from the foods you eat. Your kidneys take uric acid out of your blood and put it into urine so that it can leave your body. But...

  • Keeping your blood sugar in a target range reduces your risk of problems such as diabetic eye disease ( retinopathy), kidney disease ( nephropathy), and nerve disease ( neuropathy). Some people can work toward lower numbers, and some people may need higher goals. For example, some children and adolescents with...

  • Dialysis removes urea and other waste products from the blood. To find out how well dialysis is working, you will have blood tests that look at the level of urea in your blood. Usually these tests are done once a month, at the beginning of your session and again at the end. Two measures show how well dialysis is...

  • The blood uric acid test measures the amount of uric acid in a blood sample. Uric acid is produced from the natural breakdown of your body's cells and from the foods you eat. Most of the uric acid is filtered out by the kidneys and passes out of the body in urine. A small amount passes out of the body in stool. But if...

  • A magnesium test checks the level of magnesium in the blood. Magnesium is an important electrolyte needed for proper muscle, nerve, and enzyme function. It also helps the body use energy and is needed to move other electrolytes (potassium and sodium) into and out of cells. Most of the magnesium in the body is found in...

  • If you have preeclampsia or chronic kidney disease, your health professional may instruct you to check the protein content in your urine at home. Increased protein is a sign that your kidneys are being damaged. To test your urine on a daily basis,...

  • Doctors use thick and thin blood smears to determine whether you have malaria. If one test is negative and no parasites are found, you will have repeated blood smears every 8 hours for a couple of days to confirm that there is no malaria infection. Blood smears are taken most often from a finger prick. Thick and thin...

  • Antibody tests are a set of blood tests that check for specific antibodies to help clarify the diagnosis of lupus. They include: Anti-dsDNA (antibodies to DNA). Antinuclear antibody (ANA) Anti-RNP. Anti-Smith (Sm). Anti-SS-A (also called Ro)....

  • A complement test uses a blood sample to detect a group of proteins that help the body attack foreign substances. When there are a lot of foreign substances in the body, such as bacteria or viruses, a low level of complement means the body is trying...

  • An indirect Coombs test can be used to determine whether there are antibodies to the Rh factor in the mother's blood. In this case: A normal (negative) result means that the mother has not developed antibodies against the fetus's blood. A negative...

  • Fetal blood sampling (FBS) is the collecting of fetal blood directly from the umbilical cord or fetus. The fetal blood is tested for signs of anemia and other blood problems. FBS is also known as cordocentesis or percutaneous umbilical cord blood sampling. FBS is usually used when a Doppler ultrasound and/or a...

  • Covers blood tests that find out if your liver is damaged or inflamed. Discusses tests that measure bilirubin, albumin, alanine aminotransferase (ALT), and aspartate aminotransferase (AST). Discusses other possible tests to confirm diagnosis of hepatitis C.

  • An adrenocorticotropic hormone test measures the level of adrenocorticotropic hormone (ACTH) in the blood to check for problems with the pituitary gland and adrenal glands. ACTH is made in the pituitary gland in response to the release of another hormone, called corticotropin-releasing hormone (CRH), by the...

  • An alpha-fetoprotein (AFP) blood test checks the level of AFP in a pregnant woman's blood. AFP is a substance made in the liver of an unborn baby (fetus). The amount of AFP in the blood of a pregnant woman can help see whether the baby may have such problems as spina bifida and anencephaly. An AFP test can also be done...

  • An alkaline phosphatase (ALP) test measures the amount of the enzyme ALP in the blood. ALP is made mostly in the liver and in bone with some made in the intestines and kidneys. It also is made by the placenta of a pregnant woman. The liver makes more ALP than the other organs or the bones. Some conditions cause large...

  • An ammonia test measures the amount of ammonia in the blood. Most ammonia in the body forms when protein is broken down by bacteria in the intestines. The liver normally converts ammonia into urea, which is then eliminated in urine. Ammonia levels in the blood rise when the liver is not able to convert ammonia to urea...

  • Viral load is a measurement of how much HIV is present in your blood. A sample of blood is drawn and sent to a lab for testing. Results are expressed as the number of copies of the virus per milliliter of blood. Each virus is called a "copy" because...

  • For a giardia antigen test, a stool sample or fluid from the upper part of the intestines (duodenal fluid) is tested in the lab for the presence of antigens from Giardia lamblia. This test is often done at the same time as a stool analysis.

  • CD4+ cells are part of the immune system and are a type of white blood cell. White blood cells protect the body against infection. CD4+ cells are also called T-lymphocytes, T-cells, or T-helper cells. HIV invades and destroys CD4+ cells. But the...

  • An amylase test measures the amount of this enzyme in a sample of blood taken from a vein or in a sample of urine. Normally, only low levels of amylase are found in the blood or urine. But if the pancreas or salivary glands become damaged or blocked, more amylase is usually released into the blood and urine. In the...

  • Provides overview of tests used to find out what a person might be allergic to. Covers skin and blood tests. Explains why and how each test is done. Discusses risks. Explains results and offers points to consider before having tests.

  • Covers hepatitis B virus (HBV) tests that check for hepatitis B infection. Looks at most common HBV tests. Explains how tests are done and how to prepare for them. Looks at other tests that show how well the liver is working. Covers test results.

  • A phosphate test measures the amount of phosphate in a blood sample. Phosphate is a charged particle (ion) that contains the mineral phosphorus. The body needs phosphorus to build and repair bones and teeth, help nerves function, and make muscles contract. Most (about 85%) of the phosphorus contained in phosphate is...

  • The phosphate urine test measures the amount of phosphate in a sample of urine collected over 24 hours (24-hour urine test). Phosphate is a charged particle (ion) that contains the mineral phosphorus. The body needs phosphorus to build and repair bones and teeth, help nerves function, and make muscles contract. Most...

  • Discusses blood test to check level of potassium (K) in blood. Includes info on what affects potassium levels in the body such as kidney function, blood pH, and hormones. Explains how and why test is done. Covers what results mean.

  • Prothrombin time (PT) is a blood test that measures how long it takes blood to clot. A prothrombin time test can be used to check for bleeding problems. PT is also used to check whether medicine to prevent blood clots is working. A PT test may also be called an INR test. INR (international normalized ratio) stands...

  • Partial thromboplastin time (PTT) is a blood test that measures the time it takes your blood to clot. A PTT test can be used to check for bleeding problems. Blood clotting factors are needed for blood to clot (coagulation). The partial thromboplastin time is an important test because the time it takes your blood to...

  • A renin assay blood test is done to find the cause of high blood pressure (hypertension). Renin is an enzyme made by special cells in the kidneys. Renin works with aldosterone (a hormone made by the adrenal glands) and several other substances to help balance sodium and potassium levels in the blood and fluid levels in...

  • An aspartate aminotransferase (AST) test measures the amount of this enzyme in the blood. AST is normally found in red blood cells, liver, heart, muscle tissue, pancreas, and kidneys. AST formerly was called serum glutamic oxaloacetic transaminase (SGOT). Low levels of AST are normally found in the blood. When body...

  • A reticulocyte count is a blood test that measures how fast red blood cells called reticulocytes are made by the bone marrow and released into the blood. Reticulocytes are in the blood for about 2 days before developing into mature red blood cells. The reticulocyte count rises when there is a lot of blood loss or in...

  • Discusses serum osmolality test used to check for dehydration, certain poisons, cause of seizures, and other problems. Covers how it is done and how to prepare for it. Also covers what test results may mean.

  • A sodium test checks how much sodium is in the blood. Sodium is both an electrolyte and mineral. It helps keep the water (the amount of fluid inside and outside the body's cells) and electrolyte balance of the body. Sodium is also important in how nerves and muscles work. Most of the sodium in the body (about 85%)...

  • A tuberculin skin test (also called a Mantoux tuberculin test) is done to see if you have ever been exposed to tuberculosis (TB). The test is done by putting a small amount of TB protein ( antigens) under the top layer of skin on your inner forearm. If you have ever been exposed to the TB bacteria ( Mycobacterium...

  • Discusses test used to find cause of a sore throat. Covers conditions caused by fungal or bacterial infection. Covers how test is done. Looks at what results might mean.

  • When muscles use energy, they release a waste product called creatinine into the blood. The kidneys then filter creatinine from the blood. From the kidneys, creatinine passes out of the body through the urinary tract. If the kidneys are not functioning normally, high amounts of creatinine remain in the blood while low...

  • An alanine aminotransferase (ALT) test measures the amount of this enzyme in the blood. ALT is found mainly in the liver, but also in smaller amounts in the kidneys, heart, muscles, and pancreas. ALT was formerly called serum glutamic pyruvic transaminase (SGPT). ALT is measured to see if the liver is damaged or...

  • The test for Tay-Sachs disease measures the amount of an enzyme called hexosaminidase A (hex A) in the blood. Hex A breaks down fatty substances in the brain and nerves. Tay-Sachs is an inherited disease in which the body can't break down fatty substances as it should, so the fatty substances collect in the nerve cells...

  • Covers cholesterol and triglyceride blood tests to measure fatty substances in the blood. Explains why tests are done and how to prepare. Includes possible results and what they may mean. Looks at what may affect test results.

  • Cardiac enzyme studies measure the levels of enzymes and proteins that are linked with injury of the heart muscle. The test checks for the proteins troponin I (TnI) and troponin T (TnT). The test might also check for an enzyme called creatine kinase (CK). Low levels of these proteins and enzymes are normally found in...

  • A stool test is one of many tests used to look for colorectal cancer. These tests may find cancer early, when treatment works better. Colorectal cancer affects the large intestine ( colon) and the rectum. Stool tests include: Fecal immunochemical test and stool DNA (FIT-DNA). Fecal occult blood test...

  • An antinuclear antibody (ANA) test measures the amount and pattern of antibodies in your blood that work against your own body (autoimmune reaction). The body's immune system normally attacks and destroys foreign substances such as bacteria and viruses. But in disorders known as autoimmune diseases, the immune system...

  • Joint fluid analysis is a test to look at joint fluid under a microscope for problems such as infection, gout, pseudogout, inflammation, or bleeding. The test can help find the cause of joint pain or swelling. Normally, only a small amount of joint fluid is found in a joint. Joint fluid acts as a lubricant for the...

  • An arterial blood gases (ABG) test measures the acidity ( pH) and the levels of oxygen and carbon dioxide in the blood from an artery. This test is used to find out how well your lungs are able to move oxygen into the blood and remove carbon dioxide from the blood. As blood passes through your lungs, oxygen moves...

  • A thyroid biopsy is a procedure in which a small sample of tissue is removed from the thyroid gland and looked at under a microscope for cancer, infection, or other thyroid problems. The thyroid gland is found in front of the windpipe (trachea), just below the voice box (larynx). A sample of thyroid tissue can be...

  • A viral test is done to find infection-causing viruses. Viruses grow only in living cells. Viruses cause disease by destroying or damaging the cells they infect, damaging the body's immune system, changing the genetic material ( DNA) of the cells they infect, or causing inflammation that can damage an organ. Viruses...

  • An autopsy is a thorough medical exam of a body after death. It may be done to learn about a disease or injury. Or it may be done to find out how or why a person has died. An autopsy is done by a doctor called a pathologist. This type of doctor is an expert in examining body tissues and fluids. Family members...

  • If you were exposed to ticks and you get an expanding, circular rash (erythema migrans), your doctor may treat you for Lyme disease without doing a blood test. Blood tests done in the first few weeks may not show Lyme disease even when you have the illness. This is because the body's immune system responds slowly to the...

  • Herpes tests are done to find the herpes simplex virus (HSV). An HSV infection can cause small, painful sores that look like blisters on the skin or the tissue lining ( mucous membranes) of the throat, nose, mouth, urethra, rectum, and vagina. A herpes infection may cause only a single outbreak of sores, but in many...

  • What is screening for cervical cancer? Cervical cancer screening tests can help your doctor find and treat abnormal cell changes on your cervix before they develop into cervical cancer. These tests may be done as part of a pelvic exam. What screening tests are used? Tests include: A Pap test...

  • A testosterone test checks the level of this male hormone (androgen) in the blood. Testosterone affects sexual features and development. In men, it is made in large amounts by the testicles. In both men and women, testosterone is made in small amounts by the adrenal glands, and in women, by the ovaries. The...

  • Looks at various tests used to check how well the thyroid gland is working. Covers what results might mean. Also looks at what might affect a test. Offers links to info on other tests that might be useful, including thyroid-stimulating hormone (TSH) test.

  • A toxicology test ("tox screen") checks for drugs or other chemicals in your blood, urine, or saliva. Drugs can be swallowed, inhaled, injected, or absorbed through the skin or a mucous membrane. In rare cases, a tox screen may check your stomach contents or sweat. A tox screen may check for one certain drug or for...

  • What is an abnormal Pap test? When your doctor says that your Pap test, or Pap smear, was abnormal, it means that the test found some cells on your cervix that do not look normal. A Pap test may be done as part of a woman's routine physical exam, because it's the best way to prevent cervical cancer. But having an...

  • A cone biopsy is an extensive form of a cervical biopsy. It is called a cone biopsy because a cone-shaped wedge of tissue is removed from the cervix and examined under a microscope. A cone biopsy removes abnormal tissue that is high in the cervical canal. A small amount of normal tissue around the cone-shaped wedge of...

  • A test for calcium in urine is a 24-hour test that checks the amount of calcium that is passed from the body in the urine. Calcium is the most common mineral in the body and one of the most important. The body needs it to build and fix bones and teeth, help nerves work, make muscles squeeze together, help blood clot...

  • Cryotherapy destroys abnormal tissue on the cervix by freezing it. Cryotherapy destroys some normal tissue along with the abnormal tissue. During cryotherapy, liquid carbon dioxide (CO2), which is very cold, circulates through a probe placed next to the abnormal tissue. This freezes the tissue for 2 to 3 minutes. It may...

  • A carbon dioxide (CO2) laser beam is used to: Destroy (vaporize) abnormal cervical tissue that can be seen through a magnifying viewing instrument (colposcope). Remove abnormal tissue high in the cervical canal that cannot be seen through the colposcope. The CO2 laser can be used to do a cone biopsy. To learn more...

  • The loop electrosurgical excision procedure (LEEP) is a way to remove abnormal tissue from the cervix. It is done using a fine wire loop that has a low-voltage electrical current. LEEP may be done after colposcopy and cervical biopsy have confirmed an abnormal Pap test result. In some cases, LEEP may be done instead of...

  • Discusses blood test used to check for thyroid gland problems. Explains how TSH causes thyroid gland to make hormones that help control metabolism. Covers how it is done and test results.

  • Tests for bacterial vaginosis take samples of fluid from the vagina. The samples are looked at under a microscope to see if they show signs of infection. Bacterial vaginosis is caused by a change in the balance of bacteria in the vagina. Normally, there are a lot of "good" bacteria and some "bad" bacteria in the...

  • Carbon dioxide (CO2) is a gaseous waste product from metabolism. The blood carries carbon dioxide to your lungs, where it is exhaled. More than 90% of it in your blood exists in the form of bicarbonate (HCO3). The rest of it is either dissolved carbon dioxide gas (CO2) or carbonic acid (H2CO3). Your kidneys and lungs...

  • A bilirubin test measures the amount of bilirubin in a blood sample. Bilirubin is a brownish yellow substance found in bile. It is produced when the liver breaks down old red blood cells. Bilirubin is then removed from the body through the stool (feces) and gives stool its normal color. Bilirubin circulates in the...

  • A blood alcohol test measures the amount of alcohol (ethanol) in your body. Alcohol is quickly absorbed into the blood and can be measured within minutes of having an alcoholic drink. The amount of alcohol in the blood reaches its highest level about an hour after drinking. But food in the stomach may increase the...

  • Blood normally doesn't have any bacteria or fungi in it. A blood culture is a test of a blood sample to find germs (such as bacteria or a fungus) that can cause an infection. A bacterial infection in the blood, called bacteremia, can be serious. That's because the blood can spread the bacteria to any part of the...

  • Blood type tests are done before a person gets a blood transfusion and to check a pregnant woman's blood type. Human blood is typed by certain markers (called antigens) on the surface of red blood cells. Blood type tests may also be done to see if two people are likely to be blood relatives. The most important...

  • A test for calcium in the blood checks the calcium level in the body that is not stored in the bones. Calcium is the most common mineral in the body and one of the most important. The body needs it to build and fix bones and teeth, help nerves work, make muscles squeeze together, help blood clot, and help the heart to...

  • Discusses blood test to check the different types of hemoglobin in the blood. Covers how some diseases, such as sickle cell disease, aplastic anemia, and leukemia, have abnormal types of hemoglobin. Discusses possible test results.

  • A carbon monoxide blood test is used to detect carbon monoxide poisoning. Poisoning can happen if you breathe air that contains too much carbon monoxide (CO). This gas has no color, odor, or taste, so you can't tell when you are breathing it. The test measures the amount of hemoglobin in your blood that has bonded with...

  • The carcinoembryonic antigen (CEA) test measures the amount of this protein that may appear in the blood of some people who have certain kinds of cancers, especially cancer of the large intestine ( colon and rectal cancer). It may also be present in people with cancer of the pancreas, breast, ovary, or lung. CEA is...

  • A tissue type test is a blood test that identifies substances called antigens on the surface of body cells and tissues. Checking the antigens can tell if donor tissue is safe (compatible) for transplant to another person. This test may also be called human leukocyte antigen (HLA) typing. Based on the antigens, the...

  • Chlamydia tests use a sample of body fluid or urine to see whether chlamydia bacteria ( Chlamydia trachomatis) are present and causing an infection. Chlamydia is the most common bacterial sexually transmitted infection (STI) in the United States. Tests used to find a chlamydia infection include...

  • An immunoglobulins test is done to measure the level of immunoglobulins, also known as antibodies, in your blood. Antibodies are substances made by the body's immune system in response to bacteria, viruses, fungus, animal dander, or cancer cells. Antibodies attach to the foreign substances so the immune system can...

  • An iron test checks the amount of iron in the blood to see how well iron is metabolized in the body. Iron (Fe) is a mineral needed for hemoglobin, the protein in red blood cells that carries oxygen. Iron is also needed for energy, good muscle and organ function. About 70% of the body's iron is bound to hemoglobin in...

  • A cold agglutinins blood test is done to check for conditions that cause the body to make certain types of antibodies called cold agglutinins. Cold agglutinins are normally made by the immune system in response to infection. They cause red blood cells to clump together (agglutinate) at low temperatures. Healthy...

  • A phenylketonuria (PKU) test is done to check whether a newborn baby has the enzyme needed to use phenylalanine in his or her body. Phenylalanine is an amino acid that is needed for normal growth and development. If a baby's body does not have the enzyme that changes phenylalanine into another amino acid called...

  • The human chorionic gonadotropin (hCG) test is done to check for the hormone hCG in blood or urine. Some hCG tests measure the exact amount. Some just check to see if the hormone is present. HCG is made by the placenta during pregnancy. The test can be used to see if a woman is pregnant. Or it can be done as part of a...

  • A progesterone test measures the amount of the hormone progesterone in a blood sample. Progesterone is a female hormone produced by the ovaries during release of a mature egg from an ovary (ovulation). Progesterone helps prepare the lining of the uterus (endometrium) to receive the egg if it becomes fertilized by a...

  • A complete blood count (CBC) gives important information about the kinds and numbers of cells in the blood, especially red blood cells, white blood cells, and platelets. A CBC helps your doctor check any symptoms that you may have, such as weakness, fatigue, or bruising. A CBC also helps him or her diagnose conditions...

  • A rheumatoid factor (RF) blood test measures the amount of the RF antibody present in the blood. Normally, antibodies are produced by the immune system to help destroy and get rid of invading bacteria and viruses that can cause disease. But the RF antibody can attach to normal body tissue and cause damage. A high...

  • Creatinine and creatinine clearance tests measure the level of the waste product creatinine (say "kree-AT-uh-neen") in your blood and urine. These tests tell how well your kidneys are working. Another substance, creatine (say "KREE-uh-teen"), is formed when food is changed into energy through a process called...

  • The sedimentation rate (sed rate) blood test measures how quickly red blood cells (erythrocytes) settle in a test tube in one hour. The more red cells that fall to the bottom of the test tube in one hour, the higher the sed rate. When inflammation is present in the body, certain proteins cause red blood cells to stick...

  • A total serum protein test measures the total amount of protein in the blood. It also measures the amounts of two major groups of proteins in the blood: albumin and globulin. Albumin. This is made mainly in the liver. It helps keep the blood from leaking out of blood vessels. Albumin also...

  • The serum protein electrophoresis (SPEP) test measures specific proteins in the blood to help identify some diseases. Proteins are substances made up of smaller building blocks called amino acids. Proteins carry a positive or a negative electrical charge, and they move in fluid when placed in an electrical field. Serum...

  • A sickle cell test is a blood test done to check for sickle cell trait or sickle cell disease. Sickle cell disease is an inherited blood disease that causes red blood cells to be deformed ( sickle-shaped). The red blood cells deform because they contain an abnormal type of hemoglobin, called hemoglobin S, instead of the...

  • A vitamin B12 test measures the amount of vitamin B12 in the blood. The body needs this B vitamin to make blood cells and to maintain a healthy nervous system. Vitamin B12 is found in animal products such as meat, shellfish, milk, cheese, and eggs. Most people who eat animal products are not likely to develop vitamin...

  • Coombs tests are done to find certain antibodies that attack red blood cells. Antibodies are proteins made by the immune system. Normally, antibodies bind to foreign substances, such as bacteria and viruses, and cause them to be destroyed. The following conditions cause antibodies to be made. Transfusion...

  • Discusses oral glucose tolerance test that measures glucose (blood sugar) levels. Explains that test checks for gestational diabetes, prediabetes, and diabetes. Covers the types of tests done and how to prepare for them.

  • Discusses cancer antigen 125 (CA-125) test that can help show if some types of cancer are present. Covers its use to check how well treatment for ovarian cancer is working or to see if ovarian cancer has returned. Covers possible test results.

  • As a part of the physical exam for eating disorders, a doctor may order certain tests to see whether your body is generally healthy. These may include blood or urine tests to check: Electrolyte levels. Electrolytes are minerals, such as potassium,...

  • A prolactin test measures the level of the hormone prolactin, which is made by the pituitary gland, in your blood. Pregnant women have high levels of prolactin, which helps make breast milk. During pregnancy, prolactin levels increase by 10 to 20 times. After the baby is born, prolactin stays high if you are...

  • A genetic test checks the DNA of your cells. It can find changes in your genes, or it can check the number, order, and structure of your chromosomes. Testing may be done on samples of body tissue, blood, or other body fluids such as urine or saliva. You inherit half of your genetic information from your mother and...

  • Gonorrhea tests tell if a person has this disease. They look for the bacterium, or germ, that causes gonorrhea. Testing is done on body fluid or urine samples. Gonorrhea is a sexually transmitted infection. That means it is spread through sexual contact. It does not always cause symptoms. Tests used to find a...

  • A human immunodeficiency virus (HIV) test detects HIV antibodies or antigens, or the genetic material ( DNA or RNA) of HIV in the blood or another type of sample. This can show if an HIV infection is present (HIV-positive). HIV infects white blood cells called CD4+ cells. They are part of the body's immune system that...

  • Discusses antibody test used to detect Lyme disease. Covers two types of test (enzyme-linked immunosorbent assay and Western blot test). Covers why and how they are done. Includes info on what results mean.

  • Covers monospot test (heterophil test) and EBV antibody test, blood tests used to diagnose mononucleosis (mono), which is caused by the Epstein-Barr virus. Covers how it is done and risks. Also includes info on what test results might mean.

  • A Pap test is done to look for changes in the cells of the cervix. During a Pap test, a small sample of cells from the surface of the cervix is collected by your doctor. The sample is then spread on a slide (Pap smear) or mixed in a liquid fixative (liquid-based cytology) and sent to a lab for examination under a...

  • Explains rapid strep test to test for bacteria that cause strep throat (streptococcal pharyngitis). Explains when test is done and what results mean.

  • Discusses prostate-specific antigen (PSA) test to measure amount of PSA in the blood. Explains that test is often used for cancer screening or follow-up. Covers how test is done and how to prepare for it. Discusses what results mean.

  • A rubella blood test detects antibodies that are made by the immune system to help kill the rubella virus. These antibodies remain in the bloodstream for years. The presence of certain antibodies means a recent infection, a past infection, or that you have been vaccinated against the disease. Rubella (also called...

  • Discusses test that evaluates sperm to see if there are fertility problems or if a vasectomy worked. Covers how the test is done and how to prepare. Discusses what results may mean. Lists factors like medicines or activities that may affect the test.

  • A skin or wound culture is a test to find germs (such as bacteria or a fungus) that can cause an infection. A sample of skin, tissue, or fluid is added to a substance that promotes the growth of germs. If no germs grow, the culture is negative. If germs that can cause an infection grow, the culture is positive. The type...

  • Sputum is a thick fluid made in the lungs and in the airways leading to the lungs. A sputum culture is a test to find germs (such as bacteria or a fungus) that can cause an infection. A sample of sputum is added to a substance that promotes the growth of germs. If no germs grow, the culture is negative. If germs that...

  • A stool culture is a test on a stool sample to find germs (such as bacteria or a fungus) that can cause an infection. A sample of stool is added to a substance that promotes the growth of germs. If no germs grow, the culture is negative. If germs that can cause infection grow, the culture is positive. The type of germ...

  • A sweat test measures the amount of salt chemicals (sodium and chloride) in sweat. It is done to help diagnose cystic fibrosis. Normally, sweat on the skin surface contains very little sodium and chloride. People with cystic fibrosis have 2 to 5 times the normal amount of sodium and chloride in their sweat. During the...

  • Syphilis tests tell if a person has this disease. They look for antibodies to the bacterium, or germ, that causes syphilis. Some tests look for the syphilis germ itself. Syphilis is a sexually transmitted infection. That means it is spread through sexual contact: vaginal, anal, or oral sex. Testing is done on...

  • Discusses toxoplasmosis test, a blood test that checks pregnant women for antibodies to the Toxoplasma gondii parasite. Covers why and how it is done. Also discusses what results mean.

  • A urine culture is a test to find germs (such as bacteria) in the urine that can cause an infection. Bacteria can enter through the urethra and cause a urinary tract infection (UTI). A sample of urine is added to a substance that promotes the growth of germs. If no germs grow, the culture is negative. If germs grow...

  • A vaginal wet mount (sometimes called a vaginal smear) is a test to find the cause of vaginitis, or inflammation of the vagina and the area around the vagina (vulva). Vaginitis is often caused by an infection. But it may also be caused by a reaction to vaginal products such as soap, bath oils, spermicidal jelly, or...

  • For this test, the sinus cavity is punctured with a needle, and a sample of the sinus contents is obtained. A culture and sensitivity test is often done on the sample to identify the bacteria, virus, or fungus causing the infection and to determine which medicine will be most effective in treating it. Cells taken from...

  • Catecholamines (say "kat-uh-KOH-luh-meens") are hormones made mostly by your adrenal glands as a reaction to stress. When you feel stressed, these hormones increase heart rate, blood pressure, breathing rate, muscle strength, and mental alertness. They also lower the amount of blood that goes to the skin and...

  • The D-xylose absorption test measures the level of D-xylose, a type of sugar, in a blood or urine sample. This test is done to help diagnose problems that prevent the small intestine from absorbing nutrients in food. D-xylose is normally easily absorbed by the intestines. When problems with absorption occur, D-xylose...

  • An estrogen test measures the level of the most important estrogen hormones in a blood or urine sample. It measures estradiol, estriol, and estrone. Estradiol is the most common type of estrogen measured for nonpregnant women. The amount of estradiol in a woman's blood varies throughout her menstrual cycle...

  • A ferritin blood test checks the amount of ferritin in the blood. Ferritin is a protein in the body that binds to iron; most of the iron stored in the body is bound to ferritin. Ferritin is found in the liver, spleen, skeletal muscles, and bone marrow. Only a small amount of ferritin is found in the blood. The amount of...

  • A cortisol test is done to measure the level of the hormone cortisol in the blood. The cortisol level may show problems with the adrenal glands or pituitary gland. Cortisol is made by the adrenal glands. Cortisol levels go up when the pituitary gland releases another hormone called adrenocorticotropic hormone (ACTH)...

  • A chloride test measures the level of chloride in your blood or urine. Chloride is one of the most important electrolytes in the blood. It helps keep the amount of fluid inside and outside of your cells in balance. It also helps maintain proper blood volume, blood pressure, and pH of your body fluids. Tests for sodium...

  • Karyotype is a test to identify and evaluate the size, shape, and number of chromosomes in a sample of body cells. Extra or missing chromosomes, or abnormal positions of chromosome pieces, can cause problems with a person's growth, development, and body functions.

  • The overnight dexamethasone suppression test checks to see how taking a steroid medicine called dexamethasone changes the levels of the hormone cortisol in the blood. This test checks for a condition in which large amounts of cortisol are produced by the adrenal glands ( Cushing's syndrome). Normally, when the...

  • A folate test measures the amount of folate in the blood. Folate is one of many B vitamins. The body needs folate for normal growth and to make red blood cells (RBC), white blood cells (WBC), and platelets. Folate also is important for the normal development of a baby (fetus). Folate can be measured in the liquid...

  • An aldosterone test measures the level of aldosterone (a hormone made by the adrenal glands), in the blood. Aldosterone helps regulate sodium and potassium levels in the body. This helps control blood pressure and the balance of fluids and electrolytes in the blood. The kidney hormone renin normally stimulates the...

  • A urine test checks different components of urine, a waste product made by the kidneys. It checks the color, clarity (clear or cloudy), odor, concentration, and acidity (pH) of your urine. It also checks your levels of protein, sugar, blood cells, or other substances in your urine. A urine test may be done to help find...

  • A growth hormone (GH) test measures the amount of human growth hormone (GH) in the blood. GH is made by the pituitary gland and is needed for growth. It plays an important role in how the body uses food for energy ( metabolism). The amount of GH in the blood changes during the day and is affected by exercise, sleep...

  • Explains test for galactosemia, a rare disease passed from parents to children. Covers blood or urine test that checks a newborn for enzymes needed to change galactose from milk into glucose, a sugar used for energy. Explains why and how the test is done.

  • A ketone test checks for ketones in your blood or urine. Ketones are substances that are made when the body breaks down fat for energy. Normally, your body gets the energy it needs from carbohydrate in your diet. But stored fat is broken down and ketones are made if your diet does not contain enough carbohydrates to...

  • Covers test done on a kidney stone to find out what the stone is made of. Links to info on types of stones, including calcium, uric acid, struvite, and cystine. Explains that test can help doctor decide treatment or give info on preventing more stones from forming.

  • A lactic acid test is a blood test that measures the level of lactic acid made in the body. Most of it is made by muscle tissue and red blood cells. When the oxygen level in the body is normal, carbohydrate breaks down into water and carbon dioxide. When the oxygen level is low, carbohydrate breaks down for energy and...

  • A follicle-stimulating hormone test measures the amount of follicle-stimulating hormone (FSH) in a blood sample. FSH is produced by the pituitary gland. In women, FSH helps control the menstrual cycle and the production of eggs by the ovaries. The amount of FSH varies throughout a woman's menstrual cycle and is...

  • A lipase test measures the amount of this enzyme in a blood sample. High amounts of lipase may be found in the blood when the pancreas is damaged or when the tube leading from the pancreas (pancreatic duct) to the beginning of the small intestine is...

  • A luteinizing hormone test measures the amount of luteinizing hormone (LH) in a sample of blood or urine. LH is produced by the pituitary gland. In women, LH helps regulate the menstrual cycle and egg production ( ovulation). How much LH is in a woman's body depends on the phase of her menstrual cycle. This...

  • Covers why and how parathyroid hormone tests are done. Covers what possible results might mean. Includes info on what might affect the test.

  • This test measures the amount of lead in a person's blood. Lead is a poisonous (toxic) metal that can damage the brain and other parts of the body. A lead test may be done on blood drawn from the vein, a finger (finger stick), or the heel (heel stick). A person can be exposed to lead: By eating or drinking...

  • A gastrin test measures the level of the hormone gastrin in the blood. Gastrin is produced by cells, called G cells, in the stomach lining. When food enters the stomach, G cells trigger the release of gastrin in the blood. As blood levels of gastrin rise, the stomach releases acid (gastric acid) that helps break down...

  • Discusses blood glucose tests used to diagnose diabetes and prediabetes. Covers types of tests, including fasting blood sugar, 2-hour postprandial blood sugar, random blood sugar, and oral glucose tolerance. Discusses how to prepare and what results mean.

  • Covers blood test that checks the amount of sugar (glucose) bound to hemoglobin. Explains that test is done to check how well you are managing your diabetes. Covers how it is done and discusses results.

  • Screening for prostate cancer—checking for signs of the disease when there are no symptoms—is done with the prostate-specific antigen (PSA) test. In the United States, about 12 out of 100 men will be diagnosed with prostate cancer sometime during their lifetime. But most men who are diagnosed with prostate cancer don't...

  • All cases of tuberculosis (TB) are reported to the local or state health department, because the disease can spread to others and cause outbreaks. Major health authorities keep track of TB outbreaks and encourage early testing for people who are at risk for the disease. The CDC recommends TB testing for people who...

  • Programs to screen for lead poisoning focus on finding children or adults who are likely to be exposed to lead. These programs, developed by the U.S. Centers for Disease Control and Prevention (CDC), advise local and state agencies to determine which geographic areas are the most likely to be at risk for lead exposure...

  • The human immunodeficiency virus (HIV) changes (mutates) often. Sometimes these changes make the virus resistant to a particular medicine or class of medicines, which means the medicine is no longer effective against the virus. When this happens, the medicine no longer controls virus growth (replication) or protects the...

  • Discusses high and low blood sugar levels caused by diabetes. Suggests when to check blood sugar levels. Covers symptoms. Offers home treatment and prevention tips. Includes info on diabetes emergencies.

  • Routine exams and tests At each prenatal visit, you can expect to be weighed. Your blood pressure will be checked. Your urine may also be checked for bacteria, protein, or sugar. Your doctor or midwife will track your baby's growth and position. To do this, he or she will measure the size of your uterus (fundal height)...

  • The United States Preventive Services Task Force, U.S. Centers for Disease Control and Prevention, American Academy of Pediatrics, and American College of Obstetricians and Gynecologists recommend that all pregnant women be screened for human immunodeficiency virus (HIV) infection. This is because early detection and...

  • You can most accurately pinpoint your ovulation day by monitoring your cervical mucus, your basal body temperature (BBT), and your luteinizing hormone (LH) changes with an ovulation test. During the 5 to 6 days before and on the day of ovulation, the cervix produces a type of mucus that is stretchy, slippery, thin...

  • Umbilical cord blood contains stem cells, immature cells that can grow into red or white blood cells or clotting cells. Stem cells are now used to treat a limited number of conditions, such as leukemia. They may someday be grown and used to treat...

  • The inhibin A test is done to measure the amount of this hormone in a pregnant woman's blood to see if the baby may have Down syndrome. Inhibin A is made by the placenta during pregnancy. The level of inhibin A in the blood is used in a maternal serum quadruple screening test. Generally done between 15 and 20 weeks...

  • An aldosterone test measures the level of aldosterone (a hormone made by the adrenal glands) in the urine. Aldosterone helps regulate sodium and potassium levels in the body. This helps control blood pressure and the balance of fluids and electrolytes in the blood. The kidney hormone renin normally stimulates the...

  • A test for catecholamines measures the amount of the hormones epinephrine, norepinephrine, and dopamine in the blood. These catecholamines are made by nerve tissue, the brain, and the adrenal glands. Catecholamines help the body respond to stress or fright and prepare the body for "fight-or-flight" reactions. The...

  • A cortisol test measures the level of the hormone cortisol in a 24-hour sample of urine. The cortisol level may show problems with the adrenal glands or the pituitary gland. Cortisol is made by the adrenal glands. Cortisol levels get higher when the pituitary gland releases adrenocorticotropic hormone (ACTH)...

  • An electrolyte panel is a blood test that measures the levels of electrolytes and carbon dioxide in your blood. Electrolytes are minerals, such as sodium and potassium, that are found in the body. They keep your body's fluids in balance and help...

  • Briefly discusses liver function panel, a blood test to check for liver disease. Offers links to info on other tests that check for problems with the liver.

  • Briefly discusses basic metabolic panel, a blood test that measures your sugar (glucose) level, electrolyte and fluid balance, and kidney function. Provides links to more info on specific tests such as blood urea nitrogen, creatinine, and potassium tests.

  • A comprehensive metabolic panel is a blood test that measures your sugar (glucose) level, electrolyte and fluid balance, kidney function, and liver function. Glucose is a type of sugar your body uses for energy. Electrolytes keep your body's fluids in balance. They also help keep your body working normally, including...

  • Briefly discusses lipid panel, a blood test that measures cholesterol, triglycerides, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) levels. Covers why a lipid panel might be ordered. Also covers how to prepare for test.

  • Covers blood test used to find markers of hepatitis infection. Lists types of hepatitis panels. Includes links for more info on hepatitis A, B, and C virus tests.

  • Looks at homocysteine as a test to measure homocysteine in the blood. Covers how test is done and what results mean. Explains what could affect results.

  • Discusses C-peptide test, used to tell the difference between type 1 and type 2 diabetes, find the cause of hypoglycemia, or check whether a pancreas tumor (insulinoma) was completely removed. Discusses how the test is done and how to prepare for it.

  • A chemistry screen is a blood test that measures the levels of several substances in the blood (such as electrolytes). A chemistry screen tells your doctor about your general health, helps look for certain problems, and finds out whether treatment for a specific problem is working. Some chemistry screens look at more...

  • A C-reactive protein (CRP) test is a blood test that measures the amount of a protein called C-reactive protein in your blood. C-reactive protein measures general levels of inflammation in your body. High levels of CRP are caused by infections and many long-term diseases. But a CRP test cannot show where the...

  • A viral load test measures how much human immunodeficiency virus (HIV) is in the blood. Viral load is first measured when you are diagnosed with HIV infection. This first measurement serves as the baseline. Future viral load measurements will be compared with the baseline. Since viral load can vary from day to day, the...

  • A CD4+ count is a blood test to determine how well the immune system is working in people who have been diagnosed with human immunodeficiency virus (HIV). CD4+ cells are a type of white blood cell. White blood cells are important in fighting infections. CD4+ cells are also called T-lymphocytes, T-cells, or T-helper...

  • Sputum cytology examines a sample of sputum (mucus) under a microscope to determine whether abnormal cells are present. Sputum is not the same as saliva. Sputum is produced in the lungs and in the airways leading to the lungs. Sputum has some normal lung cells in it. Sputum cytology may be done to help detect certain...

  • Discusses a test that checks urine for a protein called albumin. Covers possible kidney damage and diabetes. Explains how test is done. Discusses normal and abnormal values from the test. Covers what affects the test.

  • A human papillomavirus (HPV) test is done to check for a high-risk HPV infection in women. HPV is a sexually transmitted infection (STI). An HPV test checks for the genetic material ( DNA) of the human papillomavirus. Like a Pap test, an HPV test is done on a sample of cells collected from the cervix. There are many...

  • Discusses BRCA gene test to check chances of breast cancer if your family or personal history shows a high chance for this cancer. Covers a woman's risk of breast or ovarian cancer if she has BRCA1 or BRCA2 gene changes. Discusses possible test results.

  • Discusses test to help diagnose lung disease, lymphoma, anemia, liver disease, and also to see how well chemotherapy is working during treatment for lymphoma. Looks at possible results.

  • Hemochromatosis gene (HFE) testing is a blood test used to check for hereditary hemochromatosis, an inherited disorder that causes the body to absorb too much iron. The iron then builds up in the blood, liver, heart, pancreas, joints, skin, and other organs. In its early stages, hemochromatosis can cause joint and...

  • Discusses screening test for hereditary hemochromatosis, a genetic disorder that causes the body to absorb too much iron. Covers symptoms of hereditary hemochromatosis. Discusses who should be screened and offers reasons not to be screened.

  • Discusses test to check level of potassium (K) in urine. Includes info on what affects potassium levels in the body such as kidney function, blood pH, and hormones. Explains how and why test is done. Covers what results mean.

  • A test for sodium in the urine is a 24-hour test or a one-time (spot) test that checks for how much sodium is in the urine. Sodium is both an electrolyte and a mineral. It helps keep the water (the amount of fluid inside and outside the body's cells) and electrolyte balance of the body. Sodium is also important in how...

  • Cervical cell changes are classified according to their degree of abnormality using the Bethesda system (TBS). Further evaluation decisions are guided by the kinds of changes seen in the cells. Minor cell changes Minor cervical cell changes are also called: Atypical squamous cells (ASC). ASC is further classified...

  • The hepatitis A virus test is a blood test that shows if you have a hepatitis A infection now or had it in the past. The test looks for antibodies made by the body to fight the virus. They will be in your blood if you have a hepatitis A infection now or have had one in the past. Hepatitis A...

  • Hepatitis C virus (HCV) test is a blood test that looks for the genetic material ( RNA) of the virus that causes hepatitis or for the proteins ( antibodies) the body makes against HCV. These proteins will be present in your blood if you have a hepatitis C infection now or have had one in the past. Different tests are...

  • A postvaccination test for immunity to the hepatitis B virus (HBV) is recommended only if you: Have an impaired immune system. This can be caused by many things, such as infection with HIV or the use of medicines to prevent organ rejection. Are older than age 49. Received the hepatitis B vaccine in the buttock. (The...

  • Sexually transmitted infections (STIs) are some of the most widespread infections both in the United States and the world. STIs affect both men and women, and two-thirds of all STIs occur in people younger than 25. Exposure to an STI can occur any...

  • Experts do not agree on whether adults who don't have symptoms should have a thyroid test. The American Thyroid Association and the American Association of Clinical Endocrinologists recommend that testing be considered for those older than age 60. The U.S. Preventive Services Task Force makes no recommendation for or...

  • A1c is a test that shows the average level of blood sugar over the past 2 to 3 months. People who have diabetes usually have this test to see whether their blood sugar levels have been staying within a target range. This test is also used to...

  • Gives info on test for BNP hormone to tell how well the heart works. Tells how BNP checks for heart failure. Tells how to get ready for test. Includes what results mean. Also discusses things that affect test results, such as some health problems and medicines.

  • An antisperm antibody test looks for special proteins ( antibodies) that fight against a man's sperm in blood, vaginal fluids, or semen. The test uses a sample of sperm and adds a substance that binds only to affected sperm. Semen can cause an immune system response in either the man's or woman's body. The...

  • Lab test results usually contain some type of unit of measurement. The units provide a way to report results so that they can be compared. Usually, but not always, the same test is reported in the same units no matter which lab did the test. Units...

  • Getting tested for HIV can be scary, but the condition is treatable. So it is important to get tested if you think you have been exposed. Early detection and monitoring of HIV will help your doctor find out whether the disease is getting worse and when to start treatment. The U.S. Centers for Disease Control and...

  • Talk with your doctor about what is putting you at risk for type 2 diabetes and how often you need to be tested. The United States Preventive Services Task Force (USPSTF) recommends testing for prediabetes and type 2 diabetes in people who are...

  • Starting at age 10 or at the beginning of puberty, a child who has a body mass index (BMI) in the 85th percentile or higher for his or her age—or whose weight is more than 120% of ideal—and who has one of the following risk factors needs to be...

  • Lab tests play one role in your health care. But while it is an important role, in most cases lab tests don't provide all the information your doctor needs to make a diagnosis or treatment decisions. Unless the test results are clear—either you are pregnant or you're not—your doctor will rarely make a decision or...

  • Have your baby's cord blood collected and sent to a private cord blood bank or a public cord blood bank. Do not bank or donate your baby's cord blood. Doctors do not recommend that you bank cord blood on the slight chance that your baby will need stem cells someday. If your baby were to need stem...

  • Guides through decision to be tested for hepatitis B. Explains hepatitis B and discusses causes and lifestyles that put you at higher risk. Covers benefits and risks. Includes an interactive tool to help you make your decision.

  • Guides through decision to have a breast cancer (BRCA) gene test. Includes reasons your doctor might recommend a BRCA gene test. Lists next steps for a positive test. Covers benefits and risks. Includes an interactive tool to help you make your decision.

  • The average woman has a small chance of getting breast cancer and an even smaller chance of getting ovarian cancer. But if someone in your family has had breast or ovarian cancer, your chances of getting those cancers may be higher. And if you have 2 or 3 relatives who have had these cancers, your chances may be even...

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