Our approach to the hyponatremic patient is based on thorough history and a well-performed physical examination. Bedside evaluation will help the physician to decide whether a patient is dry, wet, or neither. Once the patient has been characterized, an appropriate diagnosis can be established. A few simple laboratory tests will be of assistance: BUN, creatinine, osmolality, uric acid, serum potassium, and spot urinary sodium and osmolality. A logical diagnosis and therapeutic approach can then be achieved.