Hyposmolality

A decreased plasma or serum osmolality (<275 mOsm/kg), reflecting an excess of water and reduced concentration of dissolved solutes (primarily sodium and its accompanying anions), and predisposing to water movement into cells with resultant cellular swelling. Possible causes are excessive fluid intake, medications (diuretics, certain antidepressants), heart failure, kidney failure, liver failure, SIADH, adrenal insufficiency, GI loss of electrolytes (vomiting, diarrhea), and drugs (alcohol, ecstasy).