Thiazide diuretics are widely used in the treatment of hypertension, yet their use is associated with electrolyte disorders. Researchers investigated the prevalence of and risk factors for hyponatremia and hypokalemia in patients taking thiazide diuretics, substance-specific risks for these electrolyte disorders, and whether the use of thiazides is associated with a higher risk of syncope and falls.

The cross-sectional analysis included all adults admitted to the ED in a one-year period whose sodium and potassium levels were measured on admission. The researchers conducted detailed chart reviews for all patients and screened for a history of syncope or falls.

Of the 20,421 patients for whom sodium and potassium measurements were available, 1,604 were taking thiazide diuretics regularly.

Acute kidney injury was more common in thiazide users than in nonusers (21.4% versus 7.2%). Hyponatremia and hypokalemia were also significantly more common in patients taking thiazides versus nonusers (22.1% versus 9.8% and 19% versus 11%, respectively). The likelihood of hyponatremia and hypokalemia rose with increasing thiazide doses. This effect varied based on the type of thiazide-the likelihood was highest with chlorthalidone and lowest with hydrochlorothiazide. Syncope and falls were significantly more common in patients taking thiazide diuretics. Thiazide use was the strongest independent predictor of syncope and falls, even after correction for the presence of hyponatremia and hypokalemia. Increasing age was also an independent risk factor for syncope and falls, and there was a trend for male sex being protective.