Urolithiasis after kidney transplantation in pediatric recipients: a single center report.

Background: Urolithiasis occurs in approximately 6% of adult kidney transplant (KTx) recipients. Limited data are available on urolithiasis after pediatric KTx. We report the incidence, management of, and risk factors for stone development in children after KTx.

Methods: We reviewed the medical records of 399 children who received KTx at our center between September 1986 and January 2003. Transplant outcomes were compared in stone formers and controls.

Results: Twenty (5%) patients, age 9+/-5 (X +/- SD) years, developed stones over the follow-up period (74+/-53 months). Time to stone presentation was 19+/-22 months post-KTx. Presenting features were urinary tract infection (UTI), 8; gross hematuria, 5; microscopic hematuria, 2; dysuria without infection, 6; difficulty voiding, 3; and silent stones, 2. Stones were removed by cystoscopy in 11 (55%) patients. Stone composition was determined in 11 patients: calcium phosphate (55%), calcium oxalate (18%), mixed calcium phosphate and oxalate (9%), and struvite (18%). Factors predisposing to stones in study patients included suture retention (n = 4), elevated urinary calcium excretion (n = 2), recurrent UTI (n = 2), and urinary stasis (n = 2). The incidence of UTI was higher (P = 0.003) and of acute rejection was lower (P = 0.02) in stone patients compared with controls. Patient and graft survival rates and the incidence of chronic rejection did not significantly differ between study patients and controls (P = NS).

Conclusions: Urolithiasis is not uncommon in pediatric KTx patients. Factors associated with post-KTx urolithiasis include retention of suture material, recurrent UTI, hypercalciuria, and urinary stasis. Treatment is associated with excellent outcome and low recurrence rate.