CRH as a diagnostic and heuristic tool in hypothalamic-pituitary diseases

The value of CRH as a diagnostic and heuristic tool in hypothalamic-pituitary diseases is discussed. Biochemical and clinical data support the concept that a single bolus injection of CRH can divide patients with secondary adrenal failure into those with hypothalamic and those with pituitary disease. The results of CRH tests in patients with isolated ACTH deficiency suggest a pituitary defect in the majority of patients with this rare disorder. CRH administration in patients with acromegaly and macroprolactinoma demonstrates that the response of the pituitary to CRH is not modulated by high levels of growth hormone or prolactin. CRH can also be used to study the type of the secondary adrenal failure due to exogenous administration of glucocorticoids or endogenous overproduction of cortisol by an adrenal adenoma. The CRH-ACTH axis in man is a highly conserved system with unique characteristics which are a prerequisite to assure vitally important stress reactions.