Hyponatremia

A serum sodium concentration below 135 mmol/L or mEq/L, typically reflecting excess total body water relative to sodium and associated with a spectrum of neurologic and systemic manifestations. Possible causes are hypervolemia (water intoxication, heart failure, liver failure, kidney failure), sodium loss (diuretics, vomiting, diarrhea, excessive sweating), hormonal issues (SIADH, adrenal insufficiency, hypothyroidism), and medications (diuretics, antidepressants, pain killers, ecstasy).