Syndrome of inappropriate antidiuretic hormone secretion associated with prolonged keterolac use

Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used analgesics. Although rare, clinicians need to keep in mind that their use may precipitate hyponatremia and syndrome of inappropriate antidiuretic hormone (SIADH), especially in high-risk patients with multiple comorbidities. In the kidneys, prostaglandins attenuate the water retention effect of antidiuretic hormone. NSAIDs cause a decrease in prostaglandins in the kidney and therefore the effect of ADH is potentiated. We report a case of SIADH that was associated with keterolac in a 65-year-old male. SIADH has not previously been reported with keterolac, a strong NSAID with comparable analgesic effect as morphine and meperidine. Keterolac may have unique properties different from other NSAIDS which may predispose to the development of hyponatremia. In our case, prolonged use of keterolac may have contributed to the development of SIADH and caution is needed when keterolac is used for prolonged duration. A review of the literature regarding development of SIADH and hyponatremia in the setting of NSAIDs is also presented.