A Case of Primary Aldosteronism Masquerading as Bartter and Gitelman Syndromes.

Primary aldosteronism (PA) is a common cause of secondary hypertension, with familial hyperaldosteronism (FH) contributing to a lesser number of cases. FH type IV, a rare subtype, has hardly been reported as a subtype of PA cases. We present a case of a 27-year-old female who presented to the emergency department with circumoral tingling and numbness. A diagnosis of hypocalcemia due to vitamin D deficiency was made. During hospital stay, she developed acute gastroenteritis and was treated with doxycycline, after which she experienced persistent hypokalemia. Further investigation revealed urinary potassium loss and metabolic alkalosis, although her blood pressure remained normal throughout her stay. Clinical exome sequencing identified a mutated variant in the calcium voltage-gated channel subunit alpha1 H (CACNA1H) gene associated with FH type IV. Elevated plasma aldosterone and suppressed renin confirmed PA. The administration of doxycycline for treating acute gastroenteritis likely precipitated hypokalemia by enhancing the expression of the mutated CACNA1H gene variant, thereby increasing aldosterone production.