Etiology	Diagnosis	Treatment
Diuretic use	Clinical; urinary sodium > 20 mEq per L	Stop diuretic therapy
Gastrointestinal loss (e.g., diarrhea, vomiting)	Clinical; urinary sodium ≤ 20 mEq per L	Intravenous fluids (normal saline)
Osmotic diuresis	Elevated glucose level, mannitol use	Correct glucose level; stop mannitol use
Salt-losing nephropathies (previously known as cerebral salt wasting)	Urinary sodium > 20 mEq per L	Isotonic or hypertonic saline; address underlying cause
Third spacing (e.g., bowel obstruction, burns)	Clinical; computed tomography	Intravenous fluids; relieve obstruction