SOMATOTROPHIC AND CORTICOTROPHIC FUNCTIONS IN PRIMARY HYPOTHYROIDISM BEFORE AND AFTER THYROXINE TREATMENT

Abstract

ABSTRACT In 12 patients with primary hypothyroidism the somatotrophic and corticotrophic functions were evaluated before and after thyroxine treatment. The results confirm a significant decrease, reversible by treatment, of plasma HGH responses to insulin-induced hypoglycaemia and to arginine infusion. Moreover, the results indicate that the impairment of the hypothalamic-pituitary function may also involve the response of plasma ACTH after provocative tests (insulin-induced hypoglycaemia and metyrapone). It must be stressed that the impairment of the corticotrophic function can be revealed only when the responses to provocative tests are evaluated by a direct assay of plasma ACTH and not by plasma corticosteroid modifications. These different responses may account for the conflicting results obtained by other investigators and may be justified by the multiple interference of the thyroid deficiency with the hypothalamic-pituitary-adrenal axis at different levels.