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)...

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...

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). Cortisol...

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...

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...

A vitamin D test measures the amount of vitamin D in the blood. The vitamin D test is also called the 25-hydroxy vitamin D, or 25(OH)D, test. 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...

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...

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...

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...

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 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...

Laparoscopy (say "lap-uh-ROSS-kuh-pee") is a type of surgery that uses very small cuts. These cuts are called incisions. The doctor puts a lighted tube through incisions in your belly. This tube is called a scope. Then the doctor puts special tools through the tube to do the surgery. The surgery may be done to diagnose...

Explains why and how a test is done 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 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 blocked.

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.

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 pituitary...

Sperm penetration tests check to see if sperm can move through cervical mucus or join with (fertilize) an egg. These tests may be done when you're having trouble getting pregnant (infertility). There are different sperm penetration tests. The sperm mucus penetration test checks if sperm can move through the cervical...

Describes colonoscopy, a screening test that examines the lining of the large intestine. Explains that the test is done to look for polyps in the colon or rectum and to check for colorectal cancer. Discusses preparing for the test and how it is done.

Explains liver biopsy, also called percutaneous liver biopsy, a test used to look for liver diseases like hepatitis, cirrhosis, hemochromatosis, and cancer. Covers how to prepare and what to expect. Includes what results mean. Also lists risks.

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.

Paracentesis is a procedure to take out fluid that has collected in the belly ( peritoneal fluid) outside the intestines. This fluid buildup is called ascites. Ascites may be caused by infection, inflammation, an injury, or other conditions, such as cirrhosis or cancer. The fluid is taken out using a thin needle put...

Getting great care at a lower price is possible. Just like when you shop for food or clothes, there are things you can do to lower your health care costs. Save by taking charge of your health Here are some things you can do to take charge of your health and lower your health care costs. Protect your health with a...

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 spinal tap (also called a lumbar puncture) is a procedure to collect and look at the fluid ( cerebrospinal fluid, or CSF) that surrounds the brain and spinal cord. During a spinal tap, a needle is carefully inserted into the spinal canal low in the back (lumbar area). Samples of CSF are collected. The samples are...

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.