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Lab Tests

Lab Tests

  • 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 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...

  • 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.

  • 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...

  • 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.

  • 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 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...

  • 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...

  • 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...

  • 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)....

  • 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...

  • 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...

  • 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...

  • 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...

  • 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...

  • 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...

  • 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...

  • 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...

  • 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...

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

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

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

  • 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...

  • 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...

  • 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.

  • 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...

  • 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.

  • 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 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...

  • 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...

  • 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 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...

  • 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...

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

  • 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...

  • 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)...

  • 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...

  • 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 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...

  • 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 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...

  • 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...

  • 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...

  • 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...

  • 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...

  • 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...

  • 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.

  • 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...

  • 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...

  • 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...

  • 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 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...

  • 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...

  • 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 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...

  • 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...

  • 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...

  • 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...

  • 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.

  • 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...

  • 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...

  • 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.

  • 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 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...

  • 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...

  • 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...

  • 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...

  • 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...

  • 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.

  • 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.

  • 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.

  • 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.

  • 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...

  • 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...

  • 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...

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