Abstract: SA-PO290
Stones and Woes: A Case of Tiopronin Associated Proteinuria
Session Information
- Trainee Case Reports - VI
October 27, 2018 | Location: Exhibit Hall, San Diego Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Trainee Case Reports
- 1002 Genetic Diseases of the Kidney: Non-Cystic
Authors
- Ali, Sehrish, Baylor College of Medicine, Houston, Texas, United States
- Awan, Ahmed A., Baylor College of Medicine, Houston, Texas, United States
- Rajendran, Prejith P., Baylor College of Medicine, Houston, Texas, United States
- Dave, Natasha Naresh, Baylor College of Medicine, Houston, Texas, United States
- Yan, Jingyin, Baylor College of Medicine, Houston, Texas, United States
Introduction
Cystinuria is a rare genetic disorder characterized by impaired renal cystine transport causing increased cystine excretion and cystine nephrolithiasis. Treatment aims at maintaining urine cystine concentration below solubility level by hydration and alkalization. Patients resistant to conservative measures or who have a high cystine excretion rates are treated with Tiopronin or D-penicillamine. Tiopronin is usually well tolerated. Here we report a rare side effect of Tiopronin induced nephrotic range proteinuria.
Case Description
A 41 year-old woman with kidney stones for six years, presented to our stone clinic with complaints of recurrent stone passage. Her past medical history is significant for multiple urological procedures for stone removal. Her stone analysis showed 100% cystine calculi. She was managed with increased hydration and potassium citrate (60meq/daily) for stone prevention and she reported good compliance to treatment. However, CT of abdomen showed recurrent bilateral staghorn renal calculi. She underwent bilateral complicated procedures, and eventually the stone burden was cleared. Given the resistance to conservative treatment, she was started on Tiopronin at 800mg per day, which was gradually increased to 1000mg per day. At six months followup, 24 hour urine test showed decreased supersaturation and increased capacity of cystine. Repeat imaging of kidneys showed no new stone formation. However, she developed proteinuria from a baseline of 0.11mg/dL to 3.8mg/dL. Initially, a lower dose of Tiopronin was attempted with no improvement in the proteinuria. Subsequently, Tiopronin was withdrawn, and a resolution of the proteinuria was noted after that.
Discussion
Tiopronin is effective in reducing cystine stones in up to 70% of patients. With a better side effect profile compared to D-penicillamine, Tiopronin is first line for patients resistant to conservative therapy. Proteinuria due to Tiopronin is a rare, dose dependent side effect that resolves with cessation of therapy. Optimal monitoring for adverse effects is still not well defined; nonetheless, clinicians remain vigilant by monitoring urine protein to creatinine ratios every three to six months while patients are on Tiopronin.