Pediatric urolithiasis in a non-endemic country: A single center experience from The Netherlands

Abstract

Objective

To provide insight in causative factors of pediatric urolithiasis in The Netherlands, a non-endemic country.

Patients and methods

Data from 71 children with urolithiasis and stone analyses between 1996 and 2010 in the Radboud University Nijmegen Medical Centre were studied retrospectively. Patients (48 boys, 23 girls, ratio 2.1:1) were aged 0.5–18.3 years (mean 8.8, SD 5.6). All stone analyses were performed with FTIR spectroscopy.

Results

Of the 49 patients with metabolic analysis, 78% showed one (n = 15) or more (n = 23) metabolic abnormalities. Forty-seven percent had hypercalciuria (n = 23), 31% had hyperoxaluria (n = 15), 29% hypocitraturia (n = 14), 10% hyperuricosuria (n = 5), 10% cystinuria (n = 5), and 6% had hypomagnesiuria (n = 3).

Sixty-one percent of the stones were composed of calcium phosphate, calcium oxalate, or a combination of those. Twenty-six percent consisted of pure or mixed magnesium ammonium phosphate, 8.3% pure or mixed urate, and 8.3% cystine.

Conclusion

Children with urolithiasis in The Netherlands show stone composition similar to other Western European countries. However, a high percentage of metabolic abnormalities (78%) was found, indicating the need for extensive evaluation of pediatric urolithiasis to find underlying causes and thereby prevent stone recurrences. A close collaboration between a pediatric nephrologist and urologist is mandatory for optimal surgical and medical treatment.

Introduction

Pediatric urolithiasis is a serious disease for the children, parents, and doctors involved because it can cause permanent kidney damage and it has a high recurrence rate. The lifetime chance of an individual having a kidney- or bladder-stone is approximately 10–15% with a nearly 60% chance of recurrence within 10 years if not treated [1]. Although usually diagnosed between the third and fourth decade of life, urolithiasis can present at all ages, including childhood.

Several studies have shown an increase in incidence and prevalence of pediatric urolithiasis over the past decades. In 2007 Vandervoort et al. described a 4.6-fold increase in admittance in New York of children with urolithiasis, comparing data from 1994 to 1996 with 2003–2005 [2]. A recent study in the United States by Routh et al. [3] described a threefold increase in pediatric urolithiasis from 18.4 per 100,000 in 1999 to 57.0 per 100,000 in 2008. Annual incidences have been reported varying from 1.8 per 100,000 children per year in Kuwait 1996–2000 [4], 6.3 per 100,000 children under 16 years of age in an Icelandic study in 1995–2000 [5], up to a prevalence of 17% in patients under 14 years of age in endemic areas like Turkey, Tunisia, and the Far East [6].

Metabolic disorders, anatomical abnormalities, urinary tract infections (UTIs), intoxications (China), and dietary and climatic factors all contribute to the risk of developing kidney stones. Koyuncu et al. [7] found that, despite conservative measures, the risk of recurrence increases threefold if at least one metabolic abnormality is present. During metabolic evaluation in children with urolithiasis, 76% of patients showed at least one abnormality in the 24-hour urine collection as an explanation for the urolithiasis [2].

This illustrates the importance of proper management protocols to optimize treatment, reduce the recurrence risk and improve outcome. Because of the large geographic variation in incidence and etiologic factors, region-specific data are needed to develop adequate management protocols. Although much research has been done on etiologic factors, there is a paucity of published data from West European countries. This study was designed to provide insight in etiologic factors of pediatric urolithiasis in The Netherlands, and compare these data with other regions.