Test Background ACTH is a 39 amino acid peptide hormone which is secreted by the pituitary gland to regulate production of steroid hormones by the adrenal cortex. It is the principal modulator of cortisol. As the effective level of cortisol rises, release of ACTH is inhibited directly at a pituitary level. Plasma ACTH levels are useful in the differential diagnosis of pituitary Cushing’s disease, Addison’s disease, autonomous ACTH-producing pituitary tumours and ectopic sources of ACTH secretion.
Clinical Indications Establishment of the aetiology of Cushing's syndrome and assessment of treatment efficacy in Cushing’s patients
Differentiation of primary from secondary causes of adrenal insufficiency
Diagnosis of ectopic ACTH secretion, eg. small cell carcinoma of the lung
Localisation of excess ACTH production
Reference Range9am: 0-30 ng/L
Midnight: 0-10 ng/L
Sample Required EDTA (lavender top) on ice rush to laboratory