Projects

Introduction

With the rising burden of paediatric urolithiasis (UL), metabolic aetiology for UL has gained special focus in children. As endemic stone belts exist within the region, there is a need to address possible associations of clinical and stone characteristics with outcomes in these children. This study aimed to determine the association of clinical, biochemical and stone characteristics with outcomes of need for surgical intervention and recurrence of stones in children with UL.

Methods

This retrospective cohort study involved a review of hospital case records of children aged 2-18years who were diagnosed to have UL at a tertiary care nephro-urology centre from January 2000 to February 2022. Electronic records for review were available from 2015 and only discharge summaries that were available were reviewed prior to 2015. Sociodemographic details, clinical features at presentation, laboratory and imaging findings, surgical intervention and time to recurrence of stones over 5yr period was noted. When available, metabolic evaluation and study of stone composition was noted. Metabolic aetiology was considered if the child had either an abnormal urinary biochemical profile or positive stone analysis for oxalate, uric acid, cystine or xanthine. Renal dysfunction was defined as estimated glomerular filtration rate using modified Schwartz formula as < 90ml/min/1.73m2.

Results

During the study period, 210 children [median age 7yrs (3,11), 68% boys, consanguinity in 9.5%, family history of stones in 12%] were diagnosed with UL. While symptoms of pain abdomen (60%) and isolated lower urinary tract symptoms [LUTS] (20.5%) were commonly noted, UL was detected incidentally in 8%. Renal parenchyma (50%) was the commonest site followed by ureter (48%), pelvis (21%) and bladder (14%). The proportion of children presenting with LUTS was significantly higher with bladder stones compared to ureteric stones (80.6% vs 19.3%, p<0.001). The stones were unilateral (55.8%) and multiple (53%), with median(IQR) size of 9.5(6,15)mm. Urinary tract infection (UTI) was noted in 17% and congenital anomalies of kidney and urinary tract (CAKUT) in 16%. In those with renal dysfunction (24%), the mean size of stones was greater in those with UTI compared to those without UTI [18.3 vs 10.7mm, p=0.008]. Amongst 68 children with available stone analysis, 65% had calcium oxalate stones. In 70% with metabolic stones [hypercalciuria (42%), hyperuricosuria (24%) and hyperoxaluria (41%)] no association with renal function, stone composition or recurrence was noted. Compared to minimally invasive surgery in 27%, open surgery undertaken in 35% was significantly associated with younger age [5.9 vs 8.6yrs, p=0.002], larger stone size [18.3 vs 10.6mm, p=0.004], pelvis stones (p=0.002) and presence of CAKUT (p=0.018). In 38% with complete follow-up data and median follow up of 13(6,46) months, recurrence was seen in 35(41%), with time to recurrence of 36(95% CI 24-96) months [Figure].