Impaired Renin Responsiveness With Secondary Hypoaldosteronism

The existence of a syndrome of "primary aldosteronopenia" was postulated by Conn in 1956,¹ and the first patient was described by Hudson et al in 1957.² Since then, several other cases have been reported.^3-15 The condition is characterized by deficiency of aldosterone production, with normal secretion of cortisol. The patients are usually asymptomatic, but they may develop symptomatic hyperkalemia⁷ and cardiac arrhythmias,^{2, 4} particularly during a low sodium diet when requirements of aldosterone increase. Plasma renin activity has not been evaluated extensively in these patients, and it has been believed generally that the primary abnormality is defective steroid biosynthesis within the adrenal cortex.⁹ This report describes the cases of two men with selective hypoaldosteronism, both of whom had inadequate sodium conservation and who developed hyperkalemia when given a low sodium diet. Of particular interest is the finding of impaired renin responsiveness, which is postulated