Diagnosing and Treating the Syndrome of Inappropriate Antidiuretic Hormone Secretion

Current treatment of hyponatremia in syndrome of inappropriate antidiuretic hormone secretion often uses therapies with limited efficacy; the most commonly chosen monotherapy treatments, fluid restriction and isotonic saline, failed to increase the serum [Na+] by ≥5 mEq/L in 55% and 64% of monotherapy treatment episodes, respectively. Appropriate laboratory tests to diagnose syndrome of inappropriate antidiuretic hormone secretion were obtained in <50% of patients; success rates in correcting hyponatremia were significantly higher when such tests were obtained. Few outcome differences were found between the United States and the European Union. A notable exception was hospital length of stay; use of tolvaptan was associated with significantly shorter length of stay in the European Union but not in the United States. Despite the availability of effective therapies, most patients with syndrome of inappropriate antidiuretic hormone secretion were discharged from the hospital still hyponatremic.