ACTH Stimulation Test – Normal Range

ACTH Stimulation Test is aimed at helping diagnose Cushing syndrome or primary or secondary adrenal insufficiency (Addison disease) and detect conditions affecting the pituitary or adrenal glands as well.

The test usually requires a vein in your arm. Or a random or 24-hour urine sample will be needed. Thus, you may be required to rest before a sample collection.

Sometimes a saliva sample may also be used. In this case, you may be instructed to refrain from eating, drinking, or brushing your teeth for a period of time (may be some time between 15 to 30 minutes) prior to the test. Remember to follow any instructions you are given.

Normal level of cortisol after ACTH stimulation: higher than 18-20(mcg/dL) or 496.58-551.76(nmol/L)
The nomal range level may vary slightly among laboratories.

If you wake up with an increased or nomal cortisol which does not drop by bedtime, it may suggest excess cortisl and Cushing syndrome. Additionally, the excess cortisol may be due to abnormal increased ACTH production by the pituitary or a tumor outside of the pituitary or abnormal production by the adrenal glands when the following cases occur.

  • the excess cortisol is not suppressed after an overnight dexamethasone suppression test
  • the 24-hour urine cortisol is elevated
  • the late-night salivary cortisol level is elevated

On the other hand, insufficient cortisol may also indicate various conditions.

  • If the person responds to an ACTH stimulation test, the problem is likely due to insufficient ACTH production by the pituitary.
  • If the person does not respond to the ACTH stimulation test, then it is more likely that the problem is based in the adrenal glands.
  • If the adrenal glands are underactive, due to pituitary dysfunction and/or insufficient ACTH production, then the person is said to have secondary adrenal insufficiency.
  • If decreased cortisol production is due to adrenal damage, then the person is said to have primary adrenal insufficiency or Addison disease.

Keywords: ACTH Stimulation Test, Cortisol, Dexamethasone Suppression Test, DST, Free Cortisol, Salivary Cortisol, Urinary Cortisol

* The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.