Normouricemia in the syndrome of inappropriate antidiuretic hormone secretion.

Hyponatremia is seen in 40% to 60% of hospitalized acquired immune deficiency syndrome (AIDS) patients. The syndrome of inappropriate antidiuretic hormone secretion (SIADH) and volume contraction are the most common causes. The serum uric acid level can be used to distinguish between these two causes of hyponatremia. Hypouricemia is the rule in SIADH, whereas hyperuricemia commonly accompanies volume contraction. This report presents an AIDS patient with SIADH and normouricemia secondary to pyrazinamide and ethambutol.