Overview

This assay helps identify the cause of hypocortisolism and hypercortisolism. In hypocortisolism, elevated ACTH suggests primary adrenal insufficiency, while normal levels point to secondary insufficiency due to pituitary or hypothalamic issues. In hypercortisolism (Cushing's syndrome), a suppressed ACTH level indicates cortisol-producing adrenal adenoma/carcinoma, primary adrenal micronodular hyperplasia, or exogenous corticosteroid use.

What is the ACTH Test?

The ACTH test measures the level of Adrenocorticotropic Hormone in your blood.

ACTH is produced by the pituitary gland (in the brain) and controls the adrenal glands, which release cortisol (the stress hormone).

This test helps evaluate how well the pituitary–adrenal axis is working.

What Is Purpose of the ACTH Test

The ACTH test is done to:

• Diagnose adrenal gland disorders
• Differentiate causes of high or low cortisol
• Evaluate pituitary gland function
• Confirm Addison’s disease
• Diagnose Cushing’s disease
• Monitor recovery after long-term steroid use

When is the ACTH Test Recommended?

✔ Symptoms of Low Cortisol (Adrenal Insufficiency)

• Chronic fatigue
• Weight loss
• Low blood pressure
• Dizziness
• Darkening of skin
• Nausea / vomiting

✔ Symptoms of High Cortisol (Cushing’s Syndrome)

• Rapid weight gain (face, belly)
• Round face (moon face)
• High blood pressure
• Diabetes
• Muscle weakness
• Thin skin, easy bruising

✔ Medical Reasons

• Suspected pituitary or adrenal disorder
• Unexplained cortisol abnormalities
• Long-term steroid therapy
• Electrolyte imbalance (low sodium, high potassium)

What Preparation for ACTH Test

ACTH is sensitive to timing and stress.

Important preparations:

• Blood sample is usually taken early morning (7–9 AM)
• Fasting may be required (follow lab advice)
• Avoid stress and heavy exercise before test
• Inform doctor about:
• Steroid medicines
• Hormonal therapy
• Birth control pills

How is the ACTH Test Done?

1. Blood sample taken from a vein in the arm.
2. Sample is kept cold and quickly processed (ACTH is unstable).
3. Results usually available within 1 day.

Sometimes done along with a Cortisol test or ACTH stimulation test.

Normal Range

👉 Typically 7–63 pg/mL (may vary by lab)

In Simple Words

The ACTH test checks how well your brain (pituitary) and adrenal glands work together to control stress hormones. It helps diagnose Addison’s disease, Cushing’s syndrome, and pituitary problems.