Adrenocorticotropic Hormone (ACTH) – Plasma Test
Sample Type: Plasma

Purpose:
This test measures the level of ACTH, a hormone produced by the pituitary gland that stimulates the adrenal glands to release cortisol. It helps evaluate adrenal and pituitary gland function and is essential in diagnosing conditions like Cushing’s syndrome, Addison’s disease, and secondary adrenal insufficiency.

About ACTH:
ACTH regulates the production of cortisol, a hormone involved in stress response, metabolism, and immune function. Abnormal ACTH levels can signal problems with the pituitary or adrenal glands.

Indications for Testing:

Symptoms of excess cortisol (e.g., weight gain, high blood pressure, round face)

Symptoms of cortisol deficiency (e.g., fatigue, weight loss, low blood pressure)

Suspected pituitary tumors or adrenal disorders

Monitoring of known endocrine conditions

Sample Collection & Handling:

Blood is drawn into a chilled EDTA tube, and plasma must be separated and frozen promptly.

The test is often done early in the morning (typically around 8 a.m.) due to ACTH's diurnal variation.

Patients may need to fast and avoid stress prior to collection.

Normal Reference Range (may vary by lab):
10–60 pg/mL (morning levels)

Clinical Significance:

High ACTH: Addison’s disease, Cushing’s disease (pituitary cause), stress, ectopic ACTH-secreting tumors

Low ACTH: Adrenal tumors, Cushing’s syndrome (adrenal cause), secondary adrenal insufficiency (pituitary dysfunction)