POS-787 UROLITHIASIS IN KIDNEY TRANSPLANT PATIENTS

Abstract

De novo or recurrent urolithiasis after kidney transplantation is a rare yet complex kidney transplant (KT) complication. Lithogenesis is favored by multiple medical and surgical factors related to transplantation. Our study aimed to estimate the prevalence of urolithiasis in KT recipients in our department, to identify main causes, and to describe the therapeutic options and evolution. This was a retrospective observational and descriptive study conducted in the nephrology, dialysis and renal transplantation department. We have collected all the KT patients who developed urolithiasis after transplantation. Were ruled out patients who received a donor gifted graft lithiasis. Among 275 KT patients, four cases of urolithiasis were identified. Primary hyperoxaluria type 1 (PH1) was diagnosed in two patients. In the first case, the patient was initially diagnosed with end-stage renal disease and tubulointerstitial nephritis secondary to multiple radiopaque urolithiasis. No specific etiology was found. The genetic testing for the most frequent Tunisian mutations in PH1 was negative. It was until one month after the transplantation when the diagnosis of PH1 was made. The graft biopsy showed calcium oxalate crystal deposition in the kidney. A new genetic test concluded then to a novel mutation named p.Pro28Ser.The second case of PH1 was diagnosed before transplantation. The patient underwent then a combined liver-kidney transplant. Unfortunately, the disease recurred on the graft within 10 months. Both patients lost their graft with return to hemodialysis. The other 2 cases of urolithiasis had no history of lithiasis preceding the transplantation. One of them, presented 9 months after an obstructive acute graft injury with a fungus ball, radiopaque lithiasis at the inferior, and the median calyx. The etiological assessment was negative. He was kept under regular ultrasound, clinical, and biological monitoring. No complications occurred. The last patient had a spontaneous elimination of his inferior calyceal calculus. Our study confirms the rarity of urolithiasis in KT recipients. PH1 was the most common cause that posed a therapeutic challenge.