Adrenal insufficiency can result from primary disorder of the adrenal gland or occurs secondarily due to deficiency in
adrenocorticotropic hormone (
ACTH) or
corticotropin-releasing hormone (CRH). To prevent adrenal crisis, it is thus important to test the remaining function of the adrenal gland. Tests for the function of the hypothalamic-pituitary-adrenal (HPA) axis are also useful for examining localization of disease causing
adrenal insufficiency. Generally, the
insulin tolerance test (ITT) is useful for examining the HPA axis in both hypothalamic and
pituitary diseases; however, ITT has a number of disadvantages. The
growth hormone-releasing peptide (GHRP)-2 test may be a useful tool for diagnosing secondary
adrenal insufficiency such as hypothalamic disorder and pituitary damage. In the present study, we examined the diagnostic usefulness of the
GHRP-2 test as a substitute for ITT in
hypopituitarism. We showed that patients with significant
ACTH response to ITT also had significant response to the
GHRP-2 test, while patients with no significant
ACTH response to ITT also had no significant response to the
GHRP-2 test. These data suggest that the
GHRP-2 test may be a useful diagnostic tool for secondary
adrenal insufficiency such as hypothalamic disorder and pituitary damage.