Abstract: SA-PO884
Citrate Therapy Outcomes in Patients With Renal Allograft Stones
Session Information
- Transplantation: Clinical - Case Reports
November 05, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
Abstract Time: 10:00 AM - 12:00 PM
Category: Transplantation
- 2002 Transplantation: Clinical
Authors
- Thomson, Holly, Mayo Foundation for Medical Education and Research, Phoenix, Arizona, United States
- Zhang, Nan, Mayo Foundation for Medical Education and Research, Phoenix, Arizona, United States
- Keddis, Mira T., Mayo Foundation for Medical Education and Research, Phoenix, Arizona, United States
Background
Renal allograft stones occur in 1% of patients, often causing morbidity. Hypocitraturia is the most significant urinary metabolic risk factor. We previously found that only 34 of 56 patients (61%) with allograft stones at our institution had urine supersaturation analysis. Here, we aim to describe treatment effectiveness of patients with stones in their allograft kidney.
Methods
Patients with kidney transplant and stones were identified by ICD-10 codes. Those with imaging-confirmed allograft stones and 2 urine supersaturation studies collected after diagnosis at least 3 months apart were included. Chart review yielded demographics, renal disease course, urine supersaturation results, stone therapies, and patient outcomes. Descriptive statistics were used to evaluate response to therapy.
Results
Urine supersaturation data were available at multiple time points in 11 patients (55% men; mean transplant age 58 years). In this group, 4 patients had ESRD due to stone related complications and 7 had a history of native stones. All developed de novo allograft stones at mean 4.9 years after transplant. Stones tended to be in the lower pole and nonocclusive at diagnosis. In all cases of known composition, stones were calcium. Mean urine citrate at first supersaturation analysis was 104 mg/24 hr (reference range >500 mg/24 hr). Potassium or sodium citrate was prescribed in 5 of 11 patients; the remaining 6 patients increased dietary citrate. Post-treatment supersaturation analysis occurred at a mean interval of 250 days. Urine citrate increased by mean 80 mg/24 hr and urine volume increased by mean 500 mL/24 hr. Despite improvement in these risk factors, 7 patients required surgical intervention. Radiologic clearance was achieved in 5 patients, in 2 of these without surgery. In both of those cases, urine citrate increased substantially over time. Graft failure occurred in 1 patient due to stone complications.
Conclusion
Clinicians should anticipate the possibility of allograft stone formation even years after kidney transplant, in patients with or without prior history of nephrolithiasis. Urine citrate is likely a key modifiable risk factor. In some cases, increasing urine citrate eliminates stone burden independently of surgical intervention.