Severe hyperkalemia during piroxicam therapy.

Severe hyperkalemia developed in an 85-year-old man after he had been receiving piroxicam treatment for several months. At admission his serum potassium level was 9.3 mEq/L; total CO2 level, 11 mmole/L; chloride level, 122 mEq/L; serum urea nitrogen level, 54 mg/dL; and creatinine level, 2.5 mg/dL. Hyperkalemia resolved after withdrawal of the drug and polystyrene sodium sulfonate therapy and the nonanion gap acidosis subsided concomitantly. His serum urea nitrogen and creatinine levels remained unchanged. He had abnormally low plasma renin activity, which gradually returned to normal, and aldosterone concentration, which remained low. The nonsteroidal drug may have impaired renin secretion, adrenal responsiveness to angiotensin, or the action of aldosterone on the renal tubule.