Additional risk factors associated with symptomatic hydrochlorothiazide-induced hyponatremia in hypertensive patients

Background. Hydrochlorothiazide is a cheap and effective antihypertensive agent but may cause hyponatremia. Even though several risk factors for hydrochlorothiazide-induced hyponatremia have been reported, this study aimed to evaluate additional risk factors for hydrochlorothiazide-induced hyponatremia in hypertensive patients. Material and methods. The inclusion criteria were: adult patients, diagnosed with hypertension and receiving hydrochlorothiazide treatment. Eligible patients were divided into two groups: with and without hyponatremia. Those with hyponatremia were identified by using the ICD-10 code E871, while those without hyponatremia were patients who did not have any reported hyponatremia until the last visit. The ratio between hyponatremia and non-hyponatremia group was 1:2. Predictors for hyponatremia were analyzed by using logistic regression analysis. Results. During the study period, there were 68 patients admitted due to symptomatic hyponatremia from hydrochlorothiazide. There were four independent factors in the model predictive of occurrence of symptomatic hydrochlorothiazide-induced hyponatremia in hypertensive patients: sex, body mass index, plasma glucose, and serum albumin. Male sex, body mass index, and serum albumin were negatively associated with occurrence of symptomatic hydrochlorothiazide-induced hyponatremia in hypertensive patients with adjusted OR of 0.099, 0.683, and 0.122, respectively. The plasma glucose had adjusted OR of 1.030 [95% CI of (1.009, 1.051)]. Conclusions. Factors associated with hydrochlorothiazide-induced symptomatic hyponatremia in hypertensive patients were sex, body mass index, plasma glucose level, and serum albumin level. The latter two risk factors have never been reported as risk factors for hydrochlorothiazide-induced symptomatic hyponatremia in hypertensive patients.