Masking by hypokalemia-primary aldosteronism with undetectable aldosterone.

Primary aldosteronism is the most common cause of secondary hypertension; however, the dynamic regulation of aldosterone by potassium is less well studied and current diagnostic recommendations are imprecise. We describe a young man who presented with resistant hypertension and severe hypokalemia. The workup initially revealed undetectable aldosterone despite acute potassium repletion. Chronic potassium supplementation eventually uncovered hyperaldosteronism. genetic studies revealed a gain-of-function mutation within an aldosterone-producing adenoma that was clinically responsive to changes in extracellular potassium. We highlight a unique presentation of Conn's syndrome and discuss the implications for the molecular mechanisms of potassium regulation of aldosterone.