Platform
Company
Endocrine & Reproductive
Review status
Currently under review
Pending specialist review and validation.
ACTH is a hormone made by your pituitary gland that signals your adrenal glands to produce cortisol. The test measures the amount of ACTH in your blood at the moment the sample is collected.
ACTH is released in pulses and follows a daily rhythm, typically higher in the early morning and lower at night. Stress, illness, and some medicines can change it. Because the hormone is delicate, proper collection and rapid handling of the sample are important for an accurate result.
ACTH testing helps your clinician find out why cortisol may be too low or too high and where the problem is coming from. It is commonly ordered when adrenal insufficiency is suspected, when Cushing syndrome is being evaluated, or when pituitary or ectopic hormone production is a concern.
Results are usually interpreted together with cortisol and sometimes with specialized stimulation or suppression tests. Understanding the source of the hormone imbalance guides treatment, which may include medication changes, addressing autoimmune disease, or evaluating for pituitary, adrenal, or other tumors.
Your ACTH result is interpreted alongside your symptoms, physical exam, time of sample collection, and other tests. A higher value can suggest that your adrenal glands are not making enough cortisol or that there is hormone production from a nonpituitary source. A lower value can occur with pituitary problems or when cortisol is elevated from an adrenal source or from steroid medicines.
Because ACTH varies through the day and is sensitive to stress and handling, your clinician may repeat the test or pair it with cortisol collected at a specific time. If results point to a hormone disorder, follow-up may include stimulation or suppression testing, imaging, or referral to an endocrinologist. Do not stop or change any medicines without medical advice.
Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.
ACTH follows a daily rhythm and is influenced by sleep and shift work. Early morning collection is often preferred, and inconsistent sleep can affect interpretation.
ACTH is unstable in blood. Using the correct collection tube, keeping the sample cool, and rapid processing help prevent falsely low results.
Glucocorticoids, steroid injections or inhalers, ketoconazole, metyrapone, mifepristone, and pasireotide can alter ACTH or cortisol and complicate interpretation.
Acute stress, severe illness, pain, and vigorous exercise can raise ACTH. Testing when stable gives a clearer picture of your baseline.
Hormonal changes in pregnancy can shift ACTH and cortisol physiology. Your clinician will interpret results in the context of pregnancy.
High dose biotin supplements and certain antibodies in the blood can interfere with some immunoassays, causing misleading results. Follow lab guidance on withholding supplements.
Oral, topical, inhaled, or injected steroids, as well as adrenal cortisol overproduction, can suppress ACTH. Tell your clinician about all recent therapies.
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