Blood Sciences Test


ACTH

Specimen

2.7 ml EDTA tube

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Special Instructions

The sample should be collected and must be received into the laboratory within 6 hr of sample collection.

Units

ng/L

Test Usage

ACTH is the pituitary hormone that stimulates production and release of cortisol by the adrenal gland. ACTH binds to cell membranes and stimulates steroidogenesis by enhancing conversion of cholesterol to pregnenolone.

The major clinical use for the measurement of ACTH is to help delineate the cause of Cushing syndrome. In patients with primary adrenal disease, ACTH levels are suppressed, while in those with a pituitary tumour or ectopic ACTH producing tumour, ACTH levels are elevated. Patients with pituitary tumours usually have ACTH levels up to two times the upper limit of normal, while the majority of patients with ectopic ACTH tumours have higher levels.

In patients with primary adrenal cortical insufficiency (Addison’s Disease), plasma ACTH is often strikingly elevated, usually above 250 ng/L. In secondary adrenocortical insufficiency, plasma ACTH is depressed, usually below 40 ng/L.

As there is no definable bottom end of the reference range for ACTH, we would not recommend its use in the diagnosis of Addisons disease.

Availability

Referred Test

Turnaround Time

3 weeks

Cannot be added on to an existing request

Specimen Labelling Procedure