Abstract

A 47-year-old woman was cured of hypokalaemia and recurrent paralysis by the excision of an adrenal adenoma. Hypertension was initially ameliorated but was not cured. Suppression of plasma renin activity was abolished when the adenoma was excised. Repeated measurement of plasma corticosteroids before operation showed a slight increase in aldosterone and normal plasma concentrations of deoxycorticosterone, corticosterone, and cortisol. No evidence of excess mineralocorticoid was obtained from measurement of the electrolyte composition of colonic fluid or of rectal potential difference, although both these variables responded normally to salt depletion and exogenous aldosterone. The diagnostic importance of the paradoxically normal colonic measurements is emphasized and the possibility is considered that the adenoma may have secreted an unidentified hormone.