What is the role of tolvaptan for management of hyponatremia?
Background Hyponatremia, a common electrolyte abnormality, is defined as a serum sodium less than 135 mEq/L.1 The condition is associated with significant morbidity and mortality. The most important complication is transient or permanent brain dysfunction resulting from the acute effects of hypo-osmolality or if the correction of hyponatremia is too fast. Hyponatremia generally occurs due to an excess of extracellular water caused by impaired water excretion. Depending on serum osmolality, hyponatremia is classified as isotonic (~280 mOsm), hypertonic (>280 mOsm), or hypotonic (<280 mOsm). Hypotonic hyponatremia can be further classified as hypovolemic, euvolemic, or hypervolemic hyponatremia based on the fluid status of the patient. Hypovolemic hyponatremia is associated with a deficit of extracellular fluid (ECF) volume and sodium.2 Causes of hypovolemic hyponatremia include: diarrhea, excessive sweating, and thiazide-type diuretics.1 Euvolemic hyponatremia is associated with a norma
