17-hydroxycorticosteroids

Alternative names:

17-OHCS

How the test is performed:

A 24-hour urine sample is needed.
The health care provider will instruct you, if necessary, to discontinue drugs that may interfere with the test.

• On day 1, urinate into the toilet upon arising in the morning.
• Collect all subsequent urine (in a special container) for the next 24-hours.
• On day 2, urinate into the container in the morning upon arising.
• Cap the container. Keep it in the refrigerator or a cool place during the collection period. Label the container with your name, the date, the time of completion, and return it as instructed.

Infant:
Thoroughly wash the area around the urethra. Open a urine collection bag (a plastic bag with an adhesive paper on one end), and place it on your infant. For males, the entire penis can be placed in the bag and the adhesive attached to the skin. For females, the bag is placed over the labia. Place a diaper over the infant (bag and all). The infant should be checked frequently and the bag changed after the infant has urinated into the bag. For active infants, this procedure may take a couple of attempts--lively infants can displace the bag, causing an inability to obtain the specimen. The urine is drained into the container for transport to the laboratory.

Deliver it to the laboratory or your health care provider as soon as possible upon completion.

The lab analyzes the sample for the amount of 17-OHCS.

How to prepare for the test:

The health care provider will instruct you, if necessary, to discontinue drugs that may interfere with the test.

If the collection is being taken from an infant, a couple of extra collection bags may be necessary.

How the test will feel:

The test involves only normal urination, and there is no discomfort.

Why the test is performed:

Cortisol is a steroid hormone released from the adrenal cortex in response to adrenocorticotrophic hormone (ACTH). Normally, cortisol levels rise and fall during the day (diurnal variation). The highest levels are seen around 6 a.m. to 8 a.m. and the lowest levels are around midnight.

Cortisol levels increase between meals and trigger the release of amino acids from skeletal muscles and fatty acids from adipose (connective) tissue. The amino acids are absorbed by the liver and converted to glucose. This is subsequently secreted into the blood to be used for energy by certain tissues such as the brain and red blood cells. The fatty acids released from the adipose tissue are used for energy by skeletal muscles, thus sparing the available glucose for use by the brain.

Cortisol (or other glucocorticoids) in pharmacological doses reduces inflammation and inhibits the immune response. Even at physiological concentrations (normal levels), cortisol probably has an effect on the immune system and the inflammatory response, especially in people subject to chronic stress. This is because stress, in general, stimulates increased release of ACTH and secondarily releases cortisol. These individuals have chronically elevated levels of cortisol.

Normally, cortisol and ACTH reciprocally regulate each other's concentration in the blood (that is cortisol levels decrease, which causes an increase in ACTH secretion). This causes an increase in cortisol synthesis, which inhibits release of ACTH. Diseases of the pituitary and adrenal glands upset this relationship.

Some fraction of plasma cortisol is also metabolized by the liver and other tissues to inactive products such as 17-OHCS, which are excreted by the body in the urine.