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Emiliani E et al, 2018: Over 30-yr Experience on the Management of Graft Stones After Renal Transplantation.

Emiliani E, Subiela JD, Regis F, Angerri O, Palou J.
Department of Urology, Fundació Puigvert, Autonomous University of Barcelona, Barcelona, Spain.

Abstract

BACKGROUND: Urolithiasis has been reported in up to 1.8% of patients after renal transplantation. Limited data are available regarding the treatment of such patients owing to this low prevalence. OBJECTIVE: To analyse a consecutive series of 2115 renal transplantations to elucidate the prevalence of renal graft stones (RGS) and their treatment.
DESIGN, SETTING, AND PARTICIPANTS: A retrospective review was performed of a consecutive series of renal transplants from 1983 to 2017. Demographic and specific data regarding symptomatology, diagnosis, and treatment of RGS were recorded.
OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Quantitative and qualitative variables were described. Differences in clinical variables were evaluated using unpaired t test. Statistical significance was set at p<0.05.
RESULTS AND LIMITATIONS: In total, 51 patients (2.4%) were diagnosed with de novo RGS. Mean stone size was 9±6.5mm, 31.4% being multiple stones. The distal ureter was the most common location (49%). Treatment modalities were extracorporeal shock wave lithotripsy (ESWL; 43.1%), active surveillance (25.4%), retrograde ureteroscopy (URS; 17.6%), antegrade URS (3.9%), percutaneous nephrolithotomy (3.9%), open approach (3.9%), and urine alkalisation (2%). Seven (13.7%) patients developed complications: two haematuria, three urinary tract infection, one steinstrasse, and one sepsis. Median follow-up was 72 mo. Overall stone-free rate was 52.9%. No significant differences were observed between mean glomerular filtration rate before and after treatment (p=0.642). There were no cases of graft loss. Limitations include the retrospective nature of the study and limited number of patients.
CONCLUSIONS: RGS is an uncommon complication. ESWL, endoscopic surgery, and surveillance have been used to treat or follow up such patients. In well-selected patients, endourological surgery appears to achieve better outcomes. RGS does not have a long-term impact on graft function or graft survival.
PATIENT SUMMARY: It is uncommon to develop stones in the transplant kidney. If such stones are properly diagnosed, several minimally invasive treatment options can yield good results while maintaining good renal function.

Eur Urol Focus. 2018 Jun 22. pii: S2405- 4569(18)30155-X. doi: 10.1016/j.euf.2018.06.007. [Epub ahead of print]

 

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Comments 1

Hans-Göran Tiselius on Wednesday, 17 October 2018 08:50

Treatment of patients with stones in renal grafts is a delicate matter that deserves particular care to avoid every kind of trauma to the only functioning kidney. Fortunately the prevalence of renal stone formations in grafts is low. In the presented series of 2115 transplanted kidneys new stone formation was diagnosed in only 2.4% (51 kidneys).

Interestingly most stones were found in the distal ureter and although the authors conclude that better results are obtained with endoscopic procedures than with SWL, as many as 43% of the treatments had been carried out with SWL. To which extent SWL was inferior to endoscopic procedures is not clear from the report.

Unfortunately stone analysis was only available in 47% of the cases of which 24.5% obviously contained calcium salts. It is of note, however, that as many as 11.7% of the stones were composed of uric acid. This proportion of uric acid was lower than that reported in a Spanish publication on stones in transplanted kidneys [publication not available for the reviewer]. My assumption is that uric acid might be an important stone constituent in those 53% of the patients for which no stone analysis had been carried out.

From a therapeutic point of view it seems highly important to collect stone material for analysis from all these patients and when infection and calcium phosphate stones can be excluded (or are less likely) give these patients alkaline citrate. Uric acid stones will be dissolved and calcium oxalate stone recurrences prevented. This will be the gentlest form of treatment of patients with stones in renal grafts.

Treatment of patients with stones in renal grafts is a delicate matter that deserves particular care to avoid every kind of trauma to the only functioning kidney. Fortunately the prevalence of renal stone formations in grafts is low. In the presented series of 2115 transplanted kidneys new stone formation was diagnosed in only 2.4% (51 kidneys). Interestingly most stones were found in the distal ureter and although the authors conclude that better results are obtained with endoscopic procedures than with SWL, as many as 43% of the treatments had been carried out with SWL. To which extent SWL was inferior to endoscopic procedures is not clear from the report. Unfortunately stone analysis was only available in 47% of the cases of which 24.5% obviously contained calcium salts. It is of note, however, that as many as 11.7% of the stones were composed of uric acid. This proportion of uric acid was lower than that reported in a Spanish publication on stones in transplanted kidneys [publication not available for the reviewer]. My assumption is that uric acid might be an important stone constituent in those 53% of the patients for which no stone analysis had been carried out. From a therapeutic point of view it seems highly important to collect stone material for analysis from all these patients and when infection and calcium phosphate stones can be excluded (or are less likely) give these patients alkaline citrate. Uric acid stones will be dissolved and calcium oxalate stone recurrences prevented. This will be the gentlest form of treatment of patients with stones in renal grafts.
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