A case of hyponatremia induced by the thiazide-like diuretic indapamide in an elderly woman

Abstract

A 72-year-old woman with a history of hypertension who had already been taking calcium channel blockers and angiotensin II receptor blockers was prescribed additional indapamide (1 mg/day) due to inadequate blood pressure control. Two weeks later, she experienced loss of appetite and fatigue. Seeking medical attention, she was diagnosed with significant hyponatremia with a serum sodium level of 110 mEq/L at a local clinic, leading to her referral and subsequent admission to our department. Although her consciousness remained clear, laboratory findings revealed a serum sodium level of 116 mEq/L, blood urea nitrogen of 7 mg/dL, blood glucose of 96 mg/dL, and plasma osmolarity of 239.8 mOsm/kg·H₂O, consistent with hypotonic hyponatremia induced by indapamide. Indapamide was discontinued and normal saline was administered. By the 6th day of hospitalization, her serum sodium level had improved to 130 mEq/L, and her symptoms had resolved.

Thiazide-like diuretics can induce hyponatremia as a side effect with diverse symptoms and variable onset. However, in this case, hyponatremia was promptly detected shortly after the initiation of indapamide therapy, and no gastrointestinal symptoms other than anorexia were observed. When initiating thiazide-like diuretics, it is essential to be vigilant for hyponatremia and to provide appropriate medication guidance to patients in addition to monitoring their serum sodium levels.