The metyrapone test evaluates how the adrenal glands respond to adrenocorticotrophic hormone (ACTH). ACTH is made in the pituitary gland and travels through the bloodstream to the adrenal glands. There it triggers the release of another hormone called cortisol.
Who is a candidate for the test?
The metyrapone test may be done if a problem is suspected in a person's:
adrenal gland, such as a tumor or other factor that keeps the gland from working correctly
How is the test performed?
Metyrapone is given in 4-6 doses over a 24-hour period, or sometimes as a single dose at 11 p.m. Metyrapone is given orally in tablet form. At 8 a.m., a blood sample is taken from a vein on the forearm or hand. First, the skin over the vein is cleaned with an antiseptic. Next, a strong rubber tube, or tourniquet, is wrapped around the upper arm. This enlarges the veins in the lower arm by restricting blood flow.
A fine needle is gently inserted into a vein and the tourniquet is removed. Blood flows from the vein through the needle. It is collected in a syringe or vial. After the needle is withdrawn, the puncture site is covered to prevent bleeding . The blood sample is sent to a lab. There, cortisol and ACTH in the blood sample are measured.
What is involved in preparation for the test?
Because metyrapone test preparation may vary, a person should ask his or her healthcare professional.
What do the test results mean?
When results of the metyrapone test are normal:
11-deoxycortisol, which is an chemical that the body turns into the hormone cortisol, rises to more than 7 micrograms per deciliter of blood (mcg/dl)
cortisol is increased to less than 10 mcg/dl
- the ACTH level is higher after metyrapone stimulation than before
Abnormal results may include:
No increase in 11-deoxycortisol may indicate:
Cushing's syndrome, a disorder caused by an overactive adrenal gland
adrenal adenoma, a non-malignant tumor in the adrenal gland
- cancer, especially adrenal or lung cancer
Tabers Cyclopedic Medical Dictionary, F.A.Davis, 1993
Illustrated Guide to Diagnostic Tests, Springhouse, 1998 / Mosby's Manual of Diagnostic and laboratory Tests, Kathleen Pagana and Timothy Pagana, 1998