CRH and lysine-vasopressin stimulation tests in the diagnosis of hypoadrenalism secondary to hypothalamic or pituitary disorders.

Ten patients with secondary hypoadrenalism have been tested with corticotropin releasing hormone (CRH) and lysine-vasopressin (LVP). One patient had isolated ACTH deficiency; 9 had deficiency of other pituitary hormones attributable to a primary pituitary disease in 3 and to an hypothalamic disorder in 6. After CRH administration, a definite increase in plasma ACTH was observed in all 6 patients with hypothalamic disorder. No response was elicited in the 3 patients with pituitary disease and in the patient with isolated ACTH deficiency. In the responsive patients. ACTH showed a delayed and prolonged pattern of response. Lysine-vasopressin administration produced an increase in plasma ACTH in 4 of the 6 hypothalamic patients and no response in those with pituitary disease and in the patient with isolated ACTH deficiency. These findings suggest that CRH represents a reliable test in differentiating hypothalamic from pituitary adrenal failure; LVP appeared a less sensitive diagnostic test.