Low-dose ACTH stimulation test

Most symptoms and signs of adrenal insufficiency are nonspecific yet common, Because the disorder is life threatening but very easy to treat, it is essential that it be accurately diagnosed. A test that is simple, inexpensive, and accurate is needed for this purpose. The tests available in the past were either expensive and not readily available (corticotropin releasing hormone), symptomatic and necessitating hospitalization (metyrapone or insulin tolerance), or not always reliable (ACTH stimulation). This last test, although easy to perform and inexpensive, uses extremely hyperphysiologic doses of ACTH to evaluate a physiologic response, This can cause false negative results, many of which are published in the literature. A physiological dose ACTH test, 1.0 mu g, has been developed that is more sensitive than the original test in cases of mild adrenal insufficiency. It is also a very sensitive way to assess pituitary-adrenal suppression after long-term treatment with glucocorticosteroids. In this situation, symptoms of the basic disease for which steroids were administered and withdrawal symptoms often complicate the picture. The 1.0 mu g ACTH test is as sensitive as the insulin tolerance test and metyrapone tests and should be used as the screening test for adrenal insufficiency whenever such testing is indicated.