Demystifying hyponatremia: A clinical guide to evaluation and management.

Hyponatremia (serum sodium <135 mEq/L) is a frequent electrolyte abnormality complicating the clinical care of hospitalized patients. Hyponatremia has been associated with an increased risk of mortality. Hyponatremia can be seen in patients with euvolemia, hypovolemia, or hypervolemia. Evaluation of hyponatremia relies on clinical assessment and estimation of serum sodium, urine electrolytes, and serum and urine osmolality in addition to other case-specific laboratory parameters. In addition, point-of-care ultrasonography is an important adjunct to physical assessment in estimation of volume status. Understanding the pathophysiology of the underlying process can lead to a timely diagnosis and appropriate management of hyponatremia.