Prolonged remission in florid Cushing's syndrome following metyrapone treatment

Two patients presenting with diabetes mellitus and hypokalaemia resulting from markedly increased ACTH and cortisol secretion are described. Neither patient showed any evidence of a tumour and both responded dramatically to treatment with metyrapone in that all abnormal clinical features disappeared, ACTH concentrations returned to normal and both patients showed prolonged remission after metyrapone treatment was stopped. One patient relapsed after a severe viral illness and the administration of dexamethasone and cortisone. It is suggested that these cases may represent an unusual form of Cushing's syndrome in which ACTH secretion is stimulated by increasing concentrations of cortisol. When these are reduced by metyrapone administration ACTH secretion falls in parallel and prolonged remission of disease may result.