Isolated glucocorticoid insufficiency.

Two cases of isolated glucocorticoid insufficiency or congenital adrenocortical unresponsiveness to ACTH-a variant of adrenocortical failure without mineralocorticoid insufficiency-are presented. Familial incidence was present only in case 1 since two of the siblings died after convulsions, possible related to hypoglycemia. The pathology specimens of one sibling were available for review showing complete lack of the fascicular zone and degenerative changes in the adrenals and evidence of increased ACTH secretion in the pituitary. In the patients who were given substitution therapy with hydrocortisone, studies of plasma renin and aldosterone revealed impairment of plasma aldosterone response to salt restriction, orthostatism and furosemide-induced diuresis combined with postural change. We conclude that in some cases of isolated glucocorticoid insufficiency, impairment of mineralocorticoid function may gradually develop, which is in contrast to the assumption of a congenital defect in the action of ACTH.