Trimethoprim-induced hyperkalemia in renal transplant recipient

Abstract

Trimethoprim-sulfamethoxazole (TMP-SMX) is an antimicrobial agent used in a variety of infections. Adverse reactions are more common in patients with AIDS but occasionally occur in immunocompetent patients. Renal toxicity is usually a hypersensitivity reaction to the sulfa component and manifests as interstitial nephritis or sulfa crystallization in the renal tubules. Reversible hyperkalemia is a rarely reported side effect of TMP-SMX therapy attributed to TMP inhibition of potassium secretion in the distal renal tubule in a manner similar to the potassium-sparing diuretic, amiloride. We report a case of hyperkalemia associated with TMP-SMX occurring in a 32-year-old renal transplant recipient with no other risk factors for hyperkalemia. He was treated with TMP-SMX (800 mg + 160 mg) two tablets QID for suspected pneumocystis jiroveci pneumonia. He developed severe hyperkalemia on day 9 posttherapy. Hyperkalemia reverted to normal with withdrawal of trimethoprim.

Keywords

• Hyperkalemia
• kidney transplant
• pneumocystis jiroveci pneumonia
• trimethoprim