Thiazide-induced hyponatremia.

We have described a case of severe acute hyponatremia developing in a patient who had been taking thiazides for the previous eight months without having any electrolyte abnormalities. The onset of the electrolyte disturbance coincided with a physician-recommended hydration regimen, which we believe unmasked a drug-related impairment of water excretion. Withdrawal of thiazide therapy promptly resulted in water diuresis and rapid correction of the hyponatremia.