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Case of drug-induced kidney stone from overuse of phenazopyridine

Suraj Pursnani, Necole M. Streeper

Department of Urology, Penn State Health Milton S. Hershey Medical Center, Hershey, Pennsylvania, USA
Address correspondence to Dr. Suraj Pursnani, Department of Urology, Penn State Milton S. Hershey Medical Center, Mail Code H055, 500 University Drive, PO Box 850, Hershey, PA 17033-0850 USA

Canadian Journal of Urology 2024, 31(3), 11911-11913.

Abstract

Drug-induced nephrolithiasis represents only 1%-2% of stone cases. Here we focus on drugs capable of crystallizing and forming stone, specifically phenazopyridine (Pyridium/Azo). This is a case of a patient who presented with a stone conglomerate in the right proximal ureter and underwent definitive treatment. Interestingly, the stone had a purple hue with FTIR spectroscopy showing stone composition of calcium oxalate (monohydrate and dihydrate) and a material resembling phenazopyridine. We retrospectively learned that she used multiple extended courses of phenazopyridine over 3 months.

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