Clinical Significance:
Adrenocorticotropic Hormone (ACTH) is secreted by the anterior pituitary gland. The major effects of ACTH are the regulation of the adrenal gland to release glucocorticoids primarily cortisol, mineralocorticoids including aldosterone, and sex steroids to supplement those produced by the gonads. ACTH secretion is controlled by corticotropin releasing factor from the hypothalamus and by negative feedback control by the glucocorticoids. Increased levels of ACTH lead to hypercortisolism, hypertension, edema and increased pigmentation. Elevated levels of ACTH are seen in Cushing’s syndrome, ectopic ACTH tumors, adrenal atrophy, adrenal adenoma or carcinoma, congenital adrenal hyperplasia, and stress. Decreased levels occur in Addison’s disease, secondary adrenal hyperplasia, hypopituitarism, hypothalamic failure and in patients on glucocorticoid therapy. Urine ACTH measurements integrate ACTH secretion over a 24 hour period minimizing the effect of diurnal variation found in plasma or serum levels.
Reference Range:
Up to 25 ng/24 hours
Procedure:
ACTH is measured by radioimmunoassay following extraction of ACTH from the specimen.
Patient Preparation:
Cortrosyn, dexamethasone, corticosteroids, and other medications that may affect pituitary secretion should be discontinued, if possible, for at least 48 hours prior to collection of specimen.
Specimen Collection:
10 ml of a 24 hour urine collection should be submitted for analysis. No special preservatives are required. Store specimen refrigerated during collection. Specimens should be frozen prior to shipping. Minimum specimen size is 5 ml.
Shipping Instructions:
Ship specimens frozen in dry ice. Provide the total volume per 24 hours.
References:
1. H Hohtari, K Salminen-Lappalainen, and T Laatikainen. Response of Plasma Endorphins, Corticotropin, Cortisol, and Luteinizing Hormone in the Corticotropin-Releasing Hormone Stimulation Test in Eumenorrheic and Amenorrheic Athletes. Fertility and Sterility 55: 276-280, 1991.
2. E Carmina, JH Levin, G Malizia, and RA Lobo. Ovine Corticotropin-Releasing Factor and Dexamethasone Responses in Hyperandrogenic Women. Fertility and Sterility 54: 251-254, 1990.