Laboratory tests for known causes of ectopic ACTH-namely, carcinoid (serotonin, 24 hour urine 5-hydroxy-indoleacteic acid), pheochromocytoma (plasma free metanephrines and normetanephrines), and medullary thyroid carcinoma (calcitonin)- were in the normal range (Table 1). This evidence concerns the gene POMC and medullary thyroid gland carcinoma.