Chemistry & Hematology Common Tests

An albumin blood test measures the amount of albumin in your blood. Low albumin levels can be a sign of liver or kidney disease or another medical condition. High levels may be a sign of dehydration.

Albumin is a protein made by your liver. Albumin enters your bloodstream and helps keep fluid from leaking out of your blood vessels into other tissues. It is also carries hormones, vitamins, and enzymes throughout your body. Without enough albumin, fluid can leak out of your blood and build up in your lungs, abdomen (belly), or other parts of your body.

An alkaline phosphatase (ALP) test measures the amount of ALP in your blood. ALP is an enzyme found in many parts of your body. Each part of your body produces a different type of ALP. Most ALP is found in your liver, bones, kidneys, and digestive system.

Abnormal levels of ALP in your blood may be a sign of a wide range of health conditions, including liver disease, bone disorders, and chronic kidney disease. But an alkaline phosphatase test alone can’t identify the source of ALP in your blood, so other tests are usually needed to make a diagnosis.

An amylase test measures the amount of amylase in your blood or urine (pee). Amylase is an enzyme, or special protein, that helps you digest carbohydrates. Most of the amylase in your body is made by your pancreas and salivary glands.

A small amount of amylase in your blood and urine is normal. But having too much or too little may be a sign of a disorder of the pancreas or salivary glands, or another medical condition.

Thyroid peroxidase is a type of protein (called an enzyme) that cells in the thyroid gland use to make thyroid hormone. If these enzymes leak out into the bloodstream (as when thyroid cells are damaged) the immune system makes antibodies against these proteins. The thyroid peroxidase antibody test measures these antibodies in the blood.

The aspartate aminotransferase (AST) blood test measures the level of the enzyme AST in the blood.

A bilirubin blood test measures the levels of bilirubin in your blood. Bilirubin is a yellowish substance made during your body’s normal process of breaking down old red blood cells. Bilirubin is found in bile, a fluid your liver makes that helps you digest food.

If your liver is healthy, it will remove most of the bilirubin from your body. If your liver is damaged, bilirubin can leak out of your liver and into your blood. When too much bilirubin gets into the bloodstream, it can cause jaundice, a condition that causes your skin and eyes to turn yellow. Signs of jaundice, along with a bilirubin blood test, can help your health care provider find out if you have liver disease.

A BUN, or blood urea nitrogen test, can provide important information about your kidney function. The main job of your kidneys is to remove waste and extra fluid from your body. If you have kidney disease, this waste material can build up in your blood. Over time, this may lead to serious health problems, including high blood pressure, anemia, and heart disease.

The BUN test measures the amount of urea nitrogen in your blood. Urea nitrogen is a waste product that your kidneys remove from your blood. Higher than normal BUN levels may be a sign that your kidneys aren’t working well.

People with early kidney disease may not have any symptoms. A BUN test can help uncover kidney problems at an early stage when treatment can be more effective.

A c-reactive protein test measures the level of c-reactive protein (CRP) in a sample of your blood. CRP is a protein that your liver makes. Normally, you have low levels of c-reactive protein in your blood. Your liver releases more CRP into your bloodstream if you have inflammation in your body. High levels of CRP may mean you have a serious health condition that causes inflammation.

This test measures the amount of a protein called CA-125 (cancer antigen 125) in a sample of your blood. CA-125 is a type of tumor marker. High levels of certain tumor markers in your blood may be a sign of cancer. If you have cancer, measuring certain tumor markers may help provide important information about how to treat your disease.

High levels of CA-125 are often found in people who have ovarian cancer. The ovaries are a pair of female reproductive glands that store ova (eggs) and make female hormones. Ovarian cancer happens when the cells in an ovary begin to grow out of control.

A calcium blood test measures the amount of calcium in your blood. If there is too much or too little calcium in the blood, it may be a sign of a wide range of medical conditions, such as bone disease, thyroid disease, parathyroid disorders, kidney disease, and other conditions.

Calcium is one of the most important minerals in your body. About 1% of the calcium in your body is in your blood. The rest is stored in your bones and teeth. Having the right amount of calcium in your blood is necessary for your nerves, muscles, and heart to work properly. It also helps blood vessels move blood throughout your body and helps release hormones that affect many body functions.

CEA stands for carcinoembryonic antigen. CEA is a protein that is a type of “tumor marker.” Tumor markers are substances that are often made by cancer cells or by normal cells in response to cancer.

High levels of CEA are normal in healthy, unborn babies. After birth, CEA levels become very low or disappear completely. So, healthy adults should have little or no CEA in their bodies.

Cancers that may cause high levels of CEA include cancers of the:

• • Colon and rectum (colorectal or bowel cancer)
  • Prostate
  • Ovary
  • Lung
  • Thyroid
  • Liver
  • Pancreas
  • Breast

If you’ve been diagnosed with a cancer that can cause high CEA levels, CEA testing may help your health care provider learn more about your cancer and chance of recovery. The test is often used with other tests to check if cancer treatment is working.

A cholesterol test is a blood test that measures the amount of cholesterol and certain fats in your blood. Cholesterol is a waxy, fat-like substance that’s found in your blood and every cell of your body. You need some cholesterol to keep your cells and organs healthy.

Your liver makes all the cholesterol your body needs. But you can also get cholesterol from the foods you eat, especially meat, eggs, poultry, and dairy products. Foods that are high in dietary fat can also make your liver produce more cholesterol.

There are two main types of cholesterol: low-density lipoprotein (LDL), or “bad” cholesterol, and high-density lipoprotein (HDL), or “good” cholesterol.

Too much LDL cholesterol in your blood increases your risk for coronary artery disease and other heart diseases. High LDL levels can cause the buildup of a sticky substance called plaque in your arteries. Over time, plaque can narrow your arteries or fully block them. When this happens, parts of your body don’t get enough blood:

• • If the blood flow to the heart is blocked, it can cause a heart attack.
  • If the blood flow to the brain is blocked, it can cause a stroke.
  • If the blood flow to the arms or legs is blocked, it can cause peripheral artery disease.

Other names for a cholesterol test: Lipid profile, Lipid panel

This test measures the amount of creatine kinase (CK) in a sample of your blood. CK is also called creatine phosphokinase (CPK).

CK is an enzyme. An enzyme is a protein that speeds up certain chemical reactions in your body. CK helps make energy. Most of the CK in your body is in your skeletal muscles. These are the muscles you use to move. You also have CK in your heart muscle and small amounts in your brain.

Normally, a small amount of CK gets into your blood from the usual wear and tear on your muscles. But if your muscles, heart, or brain tissues are damaged, larger amounts of CK leak out of your cells into your bloodstream.

A CK test is mainly used to help diagnose and monitor injuries and diseases that damage skeletal muscles and cause high levels of CK in your blood. But it may also be used for conditions that damage the heart muscle and the brain.

Other names: CK, total CK, creatine phosphokinase, CPK

Complement C3 is a blood test that measures the activity of a certain protein.

This protein is part of the complement system. The complement system is a group of nearly 60 proteins that are in blood plasma or on the surface of some cells. The proteins work with your immune system and play a role to protect the body from infections, and to remove dead cells and foreign material. Rarely, people may inherit deficiency of some complement proteins. These people are prone to certain infections or autoimmune disorders.

There are nine major complement proteins. They are labeled C1 through C9. This article describes the test that measures C3.

Complement component 4 is a blood test that measures the activity of a certain protein. This protein is part of the complement system. The complement system is a group of nearly 60 proteins that are found in the blood plasma or on the surface of some cells.

The proteins work with your immune system and play a role in protecting from infection. They also help to remove dead cells and foreign material from the body. Rarely, people may inherit deficiency of some complement proteins. These people are prone to certain infections or autoimmune disorders.

There are nine major complement proteins. They are labeled C1 through C9. This article describes the test that measures C4.

This test measures the levels of DHEA sulfate (DHEAS) in your blood. DHEAS stands for dehydroepiandrosterone sulfate. DHEAS is mostly made in the adrenal glands, two small glands located above your kidneys. Your adrenal glands help control your heart rate, blood pressure, and other body functions. They make different types of hormones you need to stay healthy. This includes cortisol, a hormone that helps with your immune system, and DHEAS, a steroid hormone.

DHEAS is a type of androgen (male sex hormone), but it’s found in both men and women. Smaller amounts of DHEAS are made in the testicles and ovaries.

DHEAS plays an important role in making the male sex hormone testosterone and the female sex hormone estrogen. DHEAS helps with the development of male sexual characteristics at puberty and reproduction for both sexes. Your DHEAS levels peak around puberty and then get lower as you age.

If your DHEAS levels are not normal, it may mean there is a problem with your adrenal glands or sex hormones (estrogen or testosterone).

Other names: DHEAS, DHEA-S, DHEA, DHEA-SO4, dehydroepiandrosterone sulfate

An estrogen test measures the level of estrogens usually in a sample of your blood, but sometimes in urine (pee).

Estrogens are a group of hormones that play a key role in female reproductive health, including puberty, menstruation, pregnancy, and menopause. Estrogens are also important for heart, bone, and brain health in males and females. But males need estrogen in much smaller amounts.

There are many types of estrogen, but only three types are commonly tested:

• • Estrone, also called E1, is the only estrogen that females continue to make after menopause. Menopause is the time after menstrual periods have stopped for a year. Males and females make estrone in the adrenal glands (glands that sit on top of each kidney), and in body fat. In females, the ovaries (the glands that contain eggs) also make estrone.
  • Estradiol, also called E2, is the main estrogen in nonpregnant females of childbearing age. It’s mostly made in the ovaries and is important for fertility (the ability to get pregnant). It also helps support brain and bone health. Males make small amounts of this estrogen in the testicles (the glands that make sperm).
  • Estriol, also called E3, is an estrogen that increases during pregnancy. The placenta (the organ that grows in the uterus to provide nutrients and oxygen to the unborn baby) makes estriol. Measuring estriol levels can help monitor the health of a pregnancy and the unborn baby. Males and nonpregnant females have very low levels of this estrogen.

A ferritin blood test measures the level of ferritin in your blood. Ferritin is a protein that stores iron inside your cells. You need iron to make healthy red blood cells. Red blood cells carry oxygen from your lungs to the rest of your body. Iron is also important for healthy muscles, bone marrow, and organs, including brain development in children.

Too little or too much iron in your body can cause serious health problems if not treated. A ferritin blood test can show how much iron you have stored in your body.

Other names: serum ferritin, serum ferritin level, ferritin serum

A prostate-specific antigen (PSA) test is a blood test that measures the level of PSA in a sample of your blood. PSA is a protein made by your prostate. The prostate is a gland in the male reproductive system. It lies just below the bladder. It makes the fluid part of semen.

It’s normal to have a low level of PSA in your blood. A high PSA level may be caused by:

• • Prostate cancer
  • An enlarged prostate (BPH) (benign prostatic hyperplasia)
  • Other common prostate problems
  • Taking certain medicines

A PSA test can’t show what is causing abnormal PSA levels. So, if your level is high, you may need other tests.

Other names: total PSA free PSA

T4 (thyroxine) is the main hormone produced by the thyroid gland. A laboratory test can be done to measure the amount of free T4 in your blood. Free T4 is the thyroxine that is not attached to a protein in the blood.

A triiodothyronine (T3) test measures the level of T3 in a sample of your blood. It’s used to help diagnose thyroid disease.

Your thyroid is a small, butterfly-shaped gland at the base of your throat. It makes two hormones, T3 and T4 (thyroxine). Hormones are chemical messengers in your bloodstream that control the actions of certain cells or organs.

Thyroid hormones work together to control the way your body uses energy. They affect your weight, heart, body temperature, muscle strength, and even your mood. In children, thyroid hormones affect growth, too.

There are two forms of T3 in your blood:

• • Free T3 is the active form that enters your tissues where it’s needed.
  • Bound T3 is attached to certain proteins which prevent it from entering your tissues. Most of your T3 is bound.

There are different tests for measuring T3:

• • A total T3 test measures both bound and free T3 together. Medical experts think that this test is the more accurate way to measure T3.
  • A free T3 test only measures free T3.

Other names: thyroid function test; total triiodothyronine, free triiodothyronine, FT3, TT3, radioimmunoassay FT3

This test measures the level of follicle-stimulating hormone (FSH) in a sample of your blood. A hormone is a chemical messenger in your bloodstream that controls the actions of certain cells or organs. FSH plays an important role in sexual development in children and fertility in adults.

This test measures the amount of G6PD in the blood. G6PD stands for glucose-6-phosphate dehydrogenase, an enzyme that helps red blood cells work properly. Red blood cells move oxygen from your lungs to every cell in your body. Your cells need oxygen to grow, reproduce, and stay healthy.

A gamma-glutamyl transferase (GGT) test measures the amount of GGT in your blood GGT is an enzyme. Enzymes are proteins that speed up certain chemical reactions in your body. Thousands of enzymes play an important role in all of your body functions. The GGT enzyme is found throughout your body, but it is mainly found in your liver.

If your liver or bile duct is damaged, GGT may leak into your bloodstream. So high levels of GGT in your blood may be a sign of liver disease or damage to the bile ducts. Bile ducts are tubes that carry bile in and out of the liver. Bile is a fluid made by the liver that is important for digestion.

A blood glucose test measures the glucose levels in your blood. Glucose is a type of sugar. It is your body’s main source of energy. A hormone called insulin helps move glucose from your bloodstream into your cells.

A hemoglobin A1C (HbA1C) test is a blood test that shows what your average blood sugar (glucose) level was over the past two to three months.

Glucose is a type of sugar in your blood that comes from the foods you eat. Your cells use glucose for energy. A hormone called insulin helps glucose get into your cells. If you have diabetes your body doesn’t make enough insulin, or your cells don’t use it well. As a result, glucose can’t get into your cells, so your blood sugar levels increase.

Glucose in your blood sticks to hemoglobin, a protein in your red blood cells. As your blood glucose levels increase, more of your hemoglobin will be coated with glucose. An A1C test measures the percentage of your red blood cells that have glucose-coated hemoglobin.

A quantitative human chorionic gonadotropin (HCG or hCG) blood test measures the specific level of HCG in the blood. HCG is a hormone produced in the body during pregnancy.

Other HCG tests include:

• • HCG urine test
  • HCG blood test — qualitative

A fecal occult blood test (FOBT) looks at a sample of your stool (poop) to check for blood. Occult blood means that you can’t see it with the naked eye. And fecal means that it is in your stool.

Blood in your stool means there is bleeding in the digestive tract. The bleeding may be caused by a variety of conditions, including:

• • Polyps, abnormal growths on the lining of the colon or rectum
  • Hemorrhoids, swollen veins in your anus or rectum
  • Diverticulosis, a condition with small pouches in the inside wall of the colon
  • Ulcers, sores in the lining of the digestive tract
  • Colitis, a type of inflammatory bowel disease
  • Colorectal cancer, a type of cancer that starts in the colon or rectum

Colorectal cancer is one of the most common types of cancer in the United States. A fecal occult blood test can screen for colorectal cancer to help find the disease early when treatment may be most effective.

Other names: FOBT, stool occult blood, occult blood test, Hemoccult test, guaiac smear test, gFOBT, immunochemical FOBT, iFOBT; FIT

This test measures the amount of immunoglobulins in your blood. Immunoglobulins are also called antibodies. Antibodies are proteins that your immune system makes to fight germs, such as viruses and bacteria. When you’re exposed to germs, your body makes unique antibodies that are specifically designed to destroy only those germs.

An immunoglobulins test usually measures three main types of immunoglobulin (Ig) antibodies that do different jobs to protect your health:

• • IgM antibodies are the first immunoglobulins your body makes after you’re exposed to germs. They provide short-term protection while your body makes other antibodies. IgM antibodies are in your blood and lymph fluid (a watery fluid that carries the cells that fight infections and diseases to all parts of your body).
  • IgG antibodies are very important for fighting infections from bacteria and viruses. Most of the immunoglobulins in your blood are IgG. You also have some IgG antibodies in all your body fluids. Your body keeps a “blueprint” of all the IgG antibodies you have made. That way, if you’re exposed to the same germs again, your immune system can quickly make more antibodies.
  • IgA antibodies protect your respiratory tract (the organs you use to breathe) and your digestive system (the organs you use to eat and digest food) from infections. You have IgA antibodies in your blood, saliva, and gastric “juices.”

An immunoglobulins blood test measures the amounts of IgM, IgG, and IgA in your blood to help diagnose different types of health conditions that may affect your immune system.

Other names: quantitative immunoglobulins, total immunoglobulins, IgG, IgM, IgA testing

The phosphorus blood test measures the amount of phosphate in the blood.

The phosphorus blood test measures the amount of phosphate in the blood.

An insulin in blood test measures the amount of insulin in a sample of your blood. Insulin is a hormone that your pancreas makes. It helps move blood glucose (blood sugar) from your bloodstream into your cells where it’s used for energy. Glucose comes from many foods you eat. It’s your body’s main source of energy.

Normally, insulin and blood glucose levels rise and fall together:

• • Blood glucose levels increase after you eat.
  • When blood glucose rises, your pancreas releases more insulin into your blood.
  • The insulin lets glucose get into your cells, which lowers your blood glucose level.
  • When your blood glucose level returns to a range that’s normal for you, your insulin levels decrease, too.

The PTH test measures the level of parathyroid hormone in the blood.

PTH stands for parathyroid hormone. It is a protein hormone released by the parathyroid gland.

The PTH test measures the level of parathyroid hormone in the blood.

PTH stands for parathyroid hormone. It is a protein hormone released by the parathyroid gland.

This test measures the level of lactate, also called lactic acid, in a sample of your blood. In certain cases, cerebrospinal fluid (CFS) may be used. Normally, you have low levels of lactate in your blood and CFS. High levels of lactate may be a sign of a wide variety of medical conditions.

Lactate is mostly made in your muscles and red blood cells when they break down food for energy. Most of the time, your cells use oxygen to break down food for energy. But if your cells can’t get enough oxygen, they can switch to another process for making energy that doesn’t use oxygen. This backup process makes lactate. Your liver and kidneys turn the lactate into glucose (sugar) that your cells use for energy.

It’s normal to have brief increases in lactate when you’re exercising or doing other hard physical work. That’s because your body uses more oxygen when you’re physically active, which triggers your cells to make energy without oxygen. Usually, your lactate levels decrease quickly when you stop the activity.

But certain medical conditions can cause a harmful buildup of lactate. If lactate levels get too high, your blood becomes too acidic. This can lead to serious health problems and a life-threatening condition called lactic acidosis.

Lipase is a type of digestive enzyme or “digestive juice.” It helps your body digest fats. Most of your lipase is made in your pancreas, an organ located behind the lower part of your stomach. Lipase is also made in your salivary (spit) glands and in your stomach.

It’s normal to have a small amount of lipase in your blood. But if the cells of your pancreas are damaged, they will release larger amounts of lipase. So high levels of lipase in your blood may mean you have pancreatitis, (an inflamed, swollen pancreas) or another type of pancreatic disease. A lipase tests can help diagnose these conditions and others.

Other names: serum lipase, lipase, LPS

This test measures the level of lactate, also called lactic acid, in a sample of your blood. In certain cases, cerebrospinal fluid (CFS) may be used. Normally, you have low levels of lactate in your blood and CFS. High levels of lactate may be a sign of a wide variety of medical conditions.

Lactate is mostly made in your muscles and red blood cells when they break down food for energy. Most of the time, your cells use oxygen to break down food for energy. But if your cells can’t get enough oxygen, they can switch to another process for making energy that doesn’t use oxygen. This backup process makes lactate. Your liver and kidneys turn the lactate into glucose (sugar) that your cells use for energy.

It’s normal to have brief increases in lactate when you’re exercising or doing other hard physical work. That’s because your body uses more oxygen when you’re physically active, which triggers your cells to make energy without oxygen. Usually, your lactate levels decrease quickly when you stop the activity.

But certain medical conditions can cause a harmful buildup of lactate. If lactate levels get too high, your blood becomes too acidic. This can lead to serious health problems and a life-threatening condition called lactic acidosis.

This test measures the level of luteinizing hormone (LH). A hormone is a chemical messenger in your bloodstream that controls the actions of certain cells or organs. LH is usually measured in a sample of your blood. But in certain cases, it may be measured in urine (pee).

LH plays an important role in sexual development in children and fertility in adults:

• • In women who menstruate (have periods), LH helps control the menstrual cycle. It also triggers the release of an egg from the ovary. This is called ovulation. LH levels quickly rise just before ovulation. If you’re trying to have a baby, this monthly increase in LH tells you when you’re most likely to become pregnant.
  • In men, LH causes the testicles to make the hormone testosterone, which is important for making sperm. Normally, LH levels in men do not change very much.
  • In children, LH levels are normally low in early childhood. They begin to rise slowly in the years before puberty, usually between ages six and eight. As puberty begins LH continues to rise along with levels of other hormones. The increase in all of these hormones triggers the physical changes of puberty:
    • In girls, LH helps signal the ovaries to make the hormone estrogen. Estrogen is involved in the growth of breasts, body hair, and the start of menstruation.
    • In boys, LH helps signal the testicles to make testosterone. Testosterone is involved in the growth of facial and body hair, changes in a boy’s voice, and sperm production.

A magnesium blood test measures the amount of magnesium in a sample of your blood. Magnesium is a mineral that you get from many kinds of foods you eat. Some examples include nuts, seeds, beans, fortified breakfast cereals, green leafy vegetables, and milk.

Your body needs magnesium to help your muscles, nerves, and heart work properly. Magnesium also helps control blood pressure and blood glucose, also called blood sugar. It’s important for building strong bones, and it supports your immune system.

Magnesium is a type of electrolyte. Electrolytes are electrically charged minerals. They help control the amount of fluid and the balance of acids and bases (pH balance) in your body.

Most of your body’s magnesium is stored in your bones, organs, and other body tissue. Only a small amount is found in your blood. Your body tightly controls the amount of magnesium in your blood mainly through your:

• • Kidneys. They filter extra magnesium from your blood and get rid of it through urine (pee). If your magnesium level is low, your kidneys limit the amount lost through urine.
  • Intestines. They control how much magnesium you absorb from the foods you eat.

Abnormal levels of blood magnesium can be caused by many different conditions. So, a magnesium test may be used to help diagnose a variety of disorders.

Other names: Mg, Mag, Magnesium-Serum

A prealbumin blood test measures prealbumin levels in your blood. Prealbumin is a protein that’s made in your liver. Prealbumin helps carry thyroid hormones and vitamin A through your bloodstream. It also helps control how your body uses energy.

If your prealbumin levels are lower than normal, it may be a sign of malnutrition. Malnutrition is a condition where your body doesn’t get enough of the nutrients that you need for good health, such as protein, vitamins, and minerals.

Malnutrition can happen if you:

Don’t eat enough food
Eat enough, but don’t eat healthy, nutritious foods
Have problems absorbing nutrients
Have an increased need for nutrients because of infection, a serious injury, cancer, recovery after surgery, or other conditions
Other names: thyroxine binding prealbumin, PA, transthyretin test, transthyretin, tryptophan-rich prealbumin

A progesterone test measures the level of progesterone in a sample of your blood. Progesterone is a hormone that’s made mainly by the ovaries, which are two glands in the female reproductive system that contain eggs.

Each month, progesterone prepares your uterus for pregnancy. During a normal menstrual cycle, an ovary releases an egg and your progesterone levels begin to rise. Progesterone makes the lining of your uterus grow thicker so that a fertilized egg can attach (implant) inside of the uterus and grow into a baby.

If you don’t become pregnant, your progesterone levels will fall. The lining of your uterus will become thinner again. When your uterus starts to get rid of the extra blood and tissue, your menstrual period will begin.

If you become pregnant, progesterone levels will continue to rise to about 10 times higher than usual to support the pregnancy. High levels of progesterone prevent the uterus from contracting (squeezing) and causing pre-term labor. Much of the progesterone you need for a healthy pregnancy is made by the placenta. The placenta is the organ that grows in the uterus to provide nutrients and oxygen to the unborn baby.

A progesterone test can help show whether low progesterone levels are causing female infertility (problems getting pregnant after a year of trying) or problems during pregnancy. The test may also help diagnose certain problems with the adrenal glands that may cause high levels of progesterone in both females and males.

Other names: serum progesterone, progesterone blood test, PGSN

A prolactin (PRL) test measures the level of prolactin in a sample of your blood. Prolactin is a hormone produced by the pituitary gland, a small gland at the base of the brain. Hormones are chemical messengers in your bloodstream that control the actions of certain cells or organs.

Prolactin affects many body processes. But its main role is to signal breast tissue to grow during pregnancy and make milk for breastfeeding after birth. So, prolactin levels in pregnant women and new mothers are normally high.

In nonpregnant women and men, prolactin levels are normally low.

Having higher-than-normal prolactin levels (hyperprolactinemia) can affect the body in different ways:

• • In women, it can affect how the ovaries work and can cause menstrual problems and infertility.
  • In men, it can affect how the testicles work and can cause a lower sex drive and erectile dysfunction (ED). Also known as impotence, ED is the inability to get or maintain an erection.
  • In men and women who are not pregnant or breastfeeding, it can signal your body to start making breastmilk.

A prostate-specific antigen (PSA) test is a blood test that measures the level of PSA in a sample of your blood. PSA is a protein made by your prostate. The prostate is a gland in the male reproductive system. It lies just below the bladder. It makes the fluid part of semen.

It’s normal to have a low level of PSA in your blood. A high PSA level may be caused by:

• • Prostate cancer
  • An enlarged prostate (BPH) (benign prostatic hyperplasia)
  • Other common prostate problems
  • Taking certain medicines

A PSA test can’t show what is causing abnormal PSA levels. So, if your level is high, you may need other tests.

Other names: total PSA free PSA

A rheumatoid factor (RF) test looks for rheumatoid factor (RF) in a sample of your blood. Rheumatoid factors are proteins made by the immune system.

Normally, your immune system makes proteins called antibodies to attack germs that could make you sick. But rheumatoid factors are antibodies that sometimes attack healthy cells and tissues in your body by mistake. When this happens, you have an autoimmune disorder.

Not everyone has rheumatoid factors in their blood. And some people who have them are healthy. But if you have certain symptoms and higher levels or rheumatoid factors, you may have an autoimmune disorder or another health problem related to high RF levels.

RF testing is mostly used with other tests to help diagnose rheumatoid arthritis. Rheumatoid arthritis (RA) is a type of autoimmune disorder that damages your joints and causes pain, swelling, and stiffness. It is a chronic (long-lasting) condition that can also affect your organs and cause other symptoms.

High levels of rheumatoid factors may also be a sign of other autoimmune disorders, certain infections, and certain types of cancer.

Other names: RF Blood Test

This test measures the levels of SHBG in a sample of your blood. SHBG stands for sex hormone binding globulin. It’s a protein made mostly in your liver. It binds (attaches) to sex hormones in your blood.

SHBG helps control the amount of sex hormones that are actively working in your body. When the SHBG protein binds to sex hormones, your tissues can’t use those hormones. Your tissues can only use sex hormones that are “free,” which means they aren’t attached to proteins, such as SHBG.

An SHBG test is usually done if you have signs and/or symptoms of having too much or too little of the sex hormone testosterone. Testosterone is known as a “male” sex hormone, but females have testosterone in smaller amounts.

In adult males, testosterone controls sex drive, maintains muscle mass, and helps make sperm. In adult females, testosterone is important for healthy organs and the growth of bones and muscles. Measuring SHBG levels can provide information about how much of your testosterone is active in the tissues of your body.

Other names: testosterone-estrogen binding globulin, TeBG

TSH stands for thyroid stimulating hormone. A TSH test is a blood test that measures this hormone. TSH levels that are too high or too low may be a sign of a thyroid problem.

The thyroid is a small, butterfly-shaped gland in the front of your neck. Your thyroid makes hormones that control how your body uses energy. Thyroid hormones affect nearly every organ in your body, including your heart. They help control your weight, body temperature, muscle strength, and even your mood. If you don’t have enough thyroid hormones in your blood, many of your body functions slow down. If you have too much, many body functions speed up.

Your thyroid is controlled by a gland in your brain, called the pituitary gland. The pituitary gland makes thyroid stimulating hormone (TSH). TSH tells your thyroid how much thyroid hormone it needs to make.

If the thyroid hormone levels in your blood are too low, your pituitary gland makes larger amounts of TSH to tell your thyroid to work harder. If your thyroid hormone levels are too high, the pituitary gland makes little or no TSH. By measuring TSH levels in your blood, you can find out if your thyroid is making the right level of hormones.

Other names: thyrotropin test