A case of oat cell carcinoma of the lung associated with ectopic production of ADH, neurophysin and ACTH.

A woman with oat cell carcinoma of the lung showed the typical findings of the syndrome of inappropriate secretion of ADH initially during her hospital course. Ectopic production of ADH was indicated. The presence of ectopic production of ACTH was then suggested after the appearance of the elevation of plasma cortisol and ACTH which was not suppressed by dexamethasone administration. The laboratory findings of metabolic alkalosis and hypokalemia were also consistent with hyperadrenocorticism. In tumor tissue obtained by biopsy, ACTH and ADH were proven to be present by radioimmunoassay as well as nicotine-stimulated-neurophysin and estrogen-stimulated-neurophysin. This was a rare case in which the simultaneous production of ADH and ACTH was clinically diagnosed. It is suggested that the elevation of neurophysins in plasma is of value in the diagnosis of ectopic production of ADH.