Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

ACTH
8411
Reference Values:
Class IgE kU/L Interpretation
0 Negative
1 0.35-0.69 Equivocal
2 0.70-3.49 Positive
3 3.50-17.4 Positive
4 17.5-49.9 Strongly positive
5 50.0-99.9 Strongly positive
6 > or =100 Strongly positive Reference values
apply to all ages.
Clinical References: Homburger HA: Allergic diseases. In Clinical Diagnosis and Management
by Laboratory Methods. 21st edition. Edited by McPherson RA, Pincus MR. WB Saunders, Publ, New
York, Chapter 53, Part VI, pp. 961-971, 2007
Adrenocorticotropic Hormone (ACTH), Plasma
Clinical Information: Adrenocorticotropic Hormone (ACTH), the primary stimulator of adrenal
cortisol production, is synthesized by the pituitary in response to corticotropin-releasing hormone
(CRH), which is released by the hypothalamus. Plasma ACTH and cortisol levels exhibit peaks (6-8
a.m.) and nadirs (11 p.m.) Cortisol, the main glucocorticoid, plays a central role in glucose metabolism
and in the body's response to stress. Only a small percentage of circulating cortisol is biologically active
(free form), with the majority of cortisol inactive (protein bound). Cortisol is inactivated in the liver and
excreted in the urine as conjugated compounds (largely 17-hydroxysteroids). Urine free cortisol levels
reflect circulating free plasma cortisol levels. Disorders of cortisol production: Hypercortisolism
-Cushing's syndrome: - Cushing's disease (pituitary ACTH-producing tumor) - Ectopic
ACTH-producing tumor - Ectopic CRH - Adrenal cortisol-producing tumor - Adrenal hyperplasia
(non-ACTH dependent, autonomous cortisol-producing adrenal nodules) Hypocortisolism -Addison's
disease-primary adrenal insufficiency -Secondary adrenal insufficiency: -Pituitary insufficiency
-Hypothalamic insufficiency -Congenital adrenal hyperplasia-defects in enzymes involved in cortisol
synthesis
Useful For: Determining the cause of hypercortisolism and hypocortisolism states
Interpretation: In a patient with hypocortisolism, an elevated adrenocorticotropic hormone (ACTH)
indicates primary adrenal insufficiency, whereas a value that is not elevated is consistent with secondary
adrenal insufficiency from a pituitary or hypothalamic cause. In a patient with hypercortisolism
(Cushing's syndrome), a suppressed value is consistent with a cortisol-producing adrenal adenoma or
carcinoma, primary adrenal micronodular hyperplasia, or exogenous corticosteroid use. Normal or
elevated ACTH in a patient with Cushing's syndrome puts the patient in the ACTH-dependent Cushing's
syndrome category. This is due to either an ACTH-producing pituitary adenoma or ectopic production
of ACTH (bronchial carcinoid, small cell lung cancer, others). Further diagnostic studies such as
dexamethasone suppression testing, corticotropin-releasing hormone stimulation testing, petrosal sinus
sampling, and imaging studies are usually necessary to define the ACTH source.
Reference Values:
10-60 pg/mL (a.m. draws)
No established reference values for p.m. draws
Pediatric reference values are the same as adults, as confirmed by peer reviewed literature.
Petersen KE: ACTH in normal children and children with pituitary and adrenal diseases. I.
Measurement in plasma by radioimmunoassay-basal values. Acta Paediatr Scand 1981;70:341-345
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