All Medical Procedures

An ANA test detects antinuclear antibodies (ANA) in your blood. Your immune system normally makes antibodies to help you fight infection. In contrast, antinuclear antibodies often attack your body's own tissues — specifically targeting each cell's nucleus.

In most cases, a positive ANA test indicates that your immune system has launched a misdirected attack on your own tissue — in other words, an autoimmune reaction. But some people have positive ANA tests even when they're healthy.

Your doctor may order an ANA test if he or she suspects you have an autoimmune disease such as lupus, rheumatoid arthritis or scleroderma.

During active surveillance for prostate cancer, your doctor closely monitors your prostate cancer for any changes. Active surveillance for prostate cancer is sometimes called watchful waiting.

No cancer treatment is provided during active surveillance for prostate cancer. This means medications, radiation and surgery aren't used. Periodic tests are done to check for signs the cancer is growing.

You might consider active surveillance for prostate cancer if your cancer is small, expected to grow very slowly, confined to one area of your prostate, and isn't causing signs or symptoms.

If you have other health problems that limit your life expectancy, active surveillance for prostate cancer may also be a reasonable approach.

During allergy skin tests, your skin is exposed to suspected allergy-causing substances (allergens) and is then observed for signs of an allergic reaction.

Along with your medical history, allergy tests may be able to confirm whether or not a particular substance you touch, breathe or eat is causing symptoms.

Bilirubin testing checks for levels of bilirubin in your blood. Bilirubin (bil-ih-ROO-bin), an orange-yellow pigment, is a waste product of the normal breakdown of red blood cells. Bilirubin passes through the liver and eventually out of the body — mostly in feces, a small amount in urine.

Before reaching the liver, bilirubin is called unconjugated, meaning uncombined. In the liver, bilirubin combines with certain sugars to create a water-soluble form called conjugated bilirubin. Conjugated bilirubin passes out of the liver, and in the colon, it is converted back into the unconjugated form en route to being excreted from the body.

Most laboratories use a test that detects conjugated bilirubin, which is called direct. By subtracting the direct bilirubin from the amount of total bilirubin, an estimate of unconjugated bilirubin, called indirect, is obtained.

Higher than normal levels of direct or indirect bilirubin may indicate different types of liver problems. Occasionally, higher bilirubin levels may indicate an increased rate of destruction of red blood cells (hemolysis).

A common blood test, the blood urea nitrogen (BUN) test reveals important information about how well your kidneys and liver are working. A BUN test measures the amount of urea nitrogen that's in your blood.

Here's how your body typically forms and gets rid of urea nitrogen:

  • Your liver produces ammonia — which contains nitrogen — after it breaks down proteins used by your body's cells.
  • The nitrogen combines with other elements, such as carbon, hydrogen and oxygen, to form urea, which is a chemical waste product.
  • The urea travels from your liver to your kidneys through your bloodstream.
  • Healthy kidneys filter urea and remove other waste products from your blood.
  • The filtered waste products leave your body through urine.

A BUN test can reveal whether your urea nitrogen levels are higher than normal, suggesting that your kidneys or liver may not be working properly.

The level of C-reactive protein (CRP), which can be measured in your blood, increases when there's inflammation in your body. Your doctor may check your C-reactive protein level treatment for infections or for other medical conditions.

A high-sensitivity C-reactive protein (hs-CRP) test, which is more sensitive than a standard test, also can be used to evaluate your risk of developing coronary artery disease, a condition in which the arteries of your heart are narrowed. Coronary artery disease can eventually lead to a heart attack.

A simple blood test measures C-reactive protein. Some researchers think that treating people with high C-reactive protein levels will lessen their risk of heart attack or stroke.

However, according to the American Heart Association, this test isn't recommended for general screening for heart disease. And it might not be helpful in determining your heart attack risk, depending on your health and lifestyle choices.

A CA 125 test measures the amount of the protein CA 125 (cancer antigen 125) in your blood.

A CA 125 test may be used to monitor certain cancers during and after treatment. In some cases, a CA 125 test may be used to look for early signs of ovarian cancer in women with a very high risk of the disease.

A CA 125 test isn't accurate enough to use for ovarian cancer screening in all women because many noncancerous conditions can increase the CA 125 level.

Many different conditions can cause an increase in CA 125, including normal conditions, such as menstruation, and noncancerous conditions, such as uterine fibroids. Certain cancers may also cause an increased level of CA 125, including ovarian, endometrial, peritoneal and fallopian tube cancers.

A complete blood count (CBC) is a blood test used to evaluate your overall health and detect a wide range of disorders, including anemia, infection and leukemia.

A complete blood count test measures several components and features of your blood, including:

  • Red blood cells, which carry oxygen
  • White blood cells, which fight infection
  • Hemoglobin, the oxygen-carrying protein in red blood cells
  • Hematocrit, the proportion of red blood cells to the fluid component, or plasma, in your blood
  • Platelets, which help with blood clotting

Abnormal increases or decreases in cell counts as revealed in a complete blood count may indicate that you have an underlying medical condition that calls for further evaluation.

A creatinine test reveals important information about your kidneys.

Creatinine is a chemical waste product that's produced by your muscle metabolism and to a smaller extent by eating meat. Healthy kidneys filter creatinine and other waste products from your blood. The filtered waste products leave your body in your urine.

If your kidneys aren't functioning properly, an increased level of creatinine may accumulate in your blood. A serum creatinine test measures the level of creatinine in your blood and gives you an estimate of how well your kidneys filter (glomerular filtration rate). A creatinine urine test can measure creatinine in your urine.

The fecal occult blood test (FOBT) is a lab test used to check stool samples for hidden (occult) blood.

Occult blood in the stool may indicate colon cancer or polyps in the colon or rectum — though not all cancers or polyps bleed.

Typically, occult blood is passed in such small amounts that it can be detected only through the chemicals used in a fecal occult blood test.

If blood is detected through a fecal occult blood test, additional tests may be needed to determine the source of the bleeding. The fecal occult blood test can only detect the presence or absence of blood — it doesn't indicate potential sources of bleeding.