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Abstract: SA-PO036

Vanishing Bactrim Stones: A Case for Urinary Alkalinization

Session Information

Category: Acute Kidney Injury

  • 102 AKI: Clinical‚ Outcomes‚ and Trials


  • Khan, Muhammad Sheheryar, Yale University, New Haven, Connecticut, United States
  • Geller, David, Yale University, New Haven, Connecticut, United States

Trimethoprim/sulfamethoxazole (TMP-SMX) is a commonly used antibiotic in the clinical setting. It is also a rare cause of renal calculi, the management of which has not been well described. Here we present a case of AKI thought to be secondary to obstructive TMP-SMX stones with rapid resolution of AKI, obstruction and stones with urinary alkalinization.

Case Description

A 94 year old man with Waldenstrom's macroglobinemia, bladder areflexia managed with chronic Foley catheter use, and baseline normal renal function (Cr 1.1 mg/dL, eGFR 62 ml/min) was treated for E. coli bacteremia with 2 double strength TMP-SMX tablets q12h for a total of 9 days. Imaging at the time showed no nephrolithiasis. He presented to the emergency department on the 9th day with decreased urine output, acute kidney injury (Cr 4.5 mg/dL), and hyperkalemia (K 6.8 meq/L). A repeat renal U/S showed the interval development of multiple bilateral renal calculi with moderate hydronephrosis. Urinalysis demonstrated birefringent crystals under polarized light, leading to a presumptive diagnosis of TMP-SMX nephrolithiasis. The patient was treated with IV and oral bicarbonate and discharged on oral bicarbonate for one month. Two weeks later, serum Cr had decreased to 1.3 mg/dL. A renal U/S done 6 weeks after alkalinization was initiated showed complete resolution of the hydronephrosis and renal calculi. Cr was 1.1 mg/dL.


Nephrolithiasis caused by sulfamethoxazole crystals use is rare, and effective medical management strategies have not been well described. Urinary alkalinization is based on the premise of increased solubility of sulfonamides at an alkaline pH. We present a case in which rapid improvement in clinical trajectory occurred soon after urinary alkalinization. This report is unique in that we demonstrate both the growth and resolution of the stones in a rapid time frame. Further study will be required to determine if this regimen is an effective alternative to ureteral stenting or nephrostomy tubes.