What is the fate of urinary stone in infants younger than one year of age
Veridiana Andrioli, Pediatric Urology Fellow1, Kerry Highmore, Assistant Professor Diagnostic Imaging1, Michael Leonard, Professor of Surgery (Urology)2, Luis Guerra, Assistant Professor, Surgery2, Kenneth Tang, Biostatistician2, Katrina Sullivan, Research Coordinator2, Jennifer Vethamuthu, Assistant Professor, Nephrology2, Victoria Myers, Medical Degree candidate3, Melise Keays, Assistant Professor of Surgery1.
1Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, ON, Canada, 2Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, ON, Canada, 3University of Ottawa, Ottawa, ON, Canada.
Renal stone disease diagnosed in the first year of life is relatively uncommon. While risk factors such as low-birthweight, furosemide exposure and metabolic disorders are well established, there exists little information regarding resolution rates and need for surgical intervention. Our study objective was to evaluate urolithiasis and renal calcification resolution rates, time to resolution, and need for surgical intervention in children in their first year of life.
We retrospectively reviewed charts of children younger than 12 months of age (corrected for prematurity) diagnosed with nephrolithiasis and/ or nephrocalcinosis in a tertiary pediatric hospital between April 2005 - 2015 that had a minimum 1 year follow-up period. Exact logistic regression was performed to assess the relationship between size of the largest stone (on either side) and the need for surgical intervention. Kaplan-Meier curves were constructed to examine time to stone resolution among those not requiring surgical intervention.
A total of 62 patients were included. The vast majority of the patients were male (38/62 (61%)). The median age was 2.9 months (post-natal age) ranged from 0 day to 17 months at the time of the diagnosis; 35 (56%) were diagnosed with stones and 10 (16%) were initially diagnosed with nephrocalcinosis and developed stones during follow-up. 67% of all stones were asymptomatic on presentation. The remaining 17 (27%) had nephrocalcinosis diagnosed on their ultrasound without stone transformation. 37% (23/62 patients) were admitted to the NICU due to prematurity, low birth weight or comorbidities. 43% (27/62 patients) were exposed to furosemide therapy for more than 2 weeks. Metabolic anomalies such as hypercalciuria and hypocitraturia were found in 56% (35/62) of patients at the time of stone/ nephrocalcinosis diagnosis. 10 infants with metabolic anomalies required medical treatment with hydrochlorothiazide or magnesium citrate. 7 patients ultimately required surgical intervention (2 external shock wave lithotripsy (ESWL), 2 ureteroscopy and stent, 2 percutaneous nephrolithotomy and 1 open pyelolithotomy). Stone size was found to predict the eventual need for surgical intervention (OR=3.52 [95%CI: 1.47, 12.78] for each 0.1 mm increase). Notably, all patients in our cohort with a ≥0.6mm stone size in their ultrasound follow up received surgical intervention. Among patients not requiring surgical intervention (n=38), the estimated median time to spontaneous resolution from urolithiasis was 1.08 years (95%CI: 0.89-1.53, range=2 months to 6 years). The median time-to-resolution from nephrocalcinosis was 1.19 years (95%CI: 0.59-2.13).
Spontaneous resolution was a common outcome for newborns and infants diagnosed with urolithiasis and nephrocalcinosis in the first year of life but high variability in time-to-resolution was observed. Only a small proportion who had confirmed stones on ultrasounds required surgical intervention (15%) and large stone size was revealed to be a predictive factor for the need for such intervention.
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