MEDULLARY THYROID CARCINOMA: ECTOPIC PRODUCTION OF PEPTIDES WITH ACTH-LIKE, CORTICOTROPHIN RELEASING FACTOR-LIKE AND PROLACTIN PRODUCTION-STIMULATING ACTIVITIES

Abstract

A 45 yr old woman had medullary thyroid carcinoma associated with Cushing''s syndrome and galactorrhea. Elevated plasma immunoreactive ACTH and cortisol were partially suppressed by i.v. dexamethasone, appreciably raised by lysine vasopressin; and urinary excretion of 17-oxogenic steroids was slightly elevated by metyrapone. A large arteriovenous increase in plasma ACTH releasing factor-like activity across the thyroid gland was observed and tumor tissue contained ACTH releasing factor-like activity. Biologically active ACTH was not detected in tumor extracts before incubation with trypsin, but after trypsinization a value of 3.2 mU per gram was obtained. Arterial plasma contained biologically active ACTH (1.5 mU/100 ml) prior to trypsinization. Venous effluent from the thyroid gland contained biologically active (9.6 mU/100 ml) and immunoreactive ACTH (970 pg/ml) before trypsinization. Tumor extracts also contained prolactin production-stimulating activity. These findings can explain the Cushing''s syndrome and the galactorrhea, both of which disappeared completely after thyroidectomy.