Nephrol Dial Transplant (2004) 19: 1659-1660
Nephrol Dial Transplant Vol. 19 No. 6 © ERA-EDTA 2004; all rights reserved
Vesicoureteral reflux and idiopathic hypercalciuria: an association by chance?
Sir,We read with much interest the recent paper by Garcia-Nieto et al. [1] on urinary calcium excretion in children with vesicoureteral reflux (VUR). The authors found that children with VUR had a higher incidence of hypercalciuria compared with those without VUR. We recently have completed our study on urinary calcium excretion in children who have had one or more documented urinary tract infections (UTIs), looking for a possible relationship between high urinary calcium excretion and risk for UTI. Since a substantial number of children in our series had uroradiological work-up which included kidney and bladder ultrasound, direct radionuclide cystography (DRCG) and Tc99m-DMSA scan, we extracted their data and analysed urinary calcium excretion with respect to the presence of VUR and renal scarring.
There were 112 children with UTI and a control group of 91 healthy children. All children in the two groups were older than 2 years. Random non-fasting urine was obtained from all children who recovered from UTI and were afebrile for at least 1 week, due to the fact that fever can enhance parathyroid hormone release leading to a subsequent increase in urinary calcium excretion [2].
Sixty-five out of 112 children with UTI were subjected to DRCG (Table 1); VUR was detected in 32 children (VUR+) and was absent in 33 children (VUR–). In VUR– children, the mean molar urinary calcium to creatinine ratio (Ca/Cr) was 0.53±0.27 (0.19±0.10 mg/mg), whereas in those with VUR+ it was 0.37±0.44 (0.13±0.16 mg/mg) (P = 0.839, Mann–Whitney U-test). If the upper normal limit for hypercalciuria is regarded as 0.56 mmol/mmol (or 0.20 mg/mg) according to Stapleton et al. [3], then 18.7% in the VUR+ group and 15.1% in the VUR– group were hypercalciuric (P>0.05, Table 1). If the upper limit for calciuria in our population aged 2–14 years was regarded as 0.99 mmol/mmol or 0.35 mg/mg (our unpublished data), then 6.2% children were hypercalciuric in the VUR+ group vs 9.1% in VUR– group (P>0.05). In the control group, only 4.4% were hypercalciuric, which did not differ from children with or without VUR.
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Neither did we find a difference in calciuria between children with normal and abnormal DMSA scan (0.44±1.08 mmol/mmol vs 0.46±0.49 mmol/mmol, Mann–Whitney U-test, P = 0.172).
In summary, we found no correlation between the presence of VUR and hypercalciuria. Renal scarring was also not associated with hypercalciuria. We speculate that the association of hypercalciuria and VUR is most probably a chance occurrence since both entities are relatively common in the general population.
Conflict of interest statement. None declared.
1Department of Pediatric Nephrology University Children's Hospital Medical School 2Department of Medical Informatics University Clinical Center Skopje Macedonia Email: vtasic{at}freemail.com.mk
References
- Garcia-Nieto V, Siverio B, Monge M, Toledo C, Molini N. Urinary calcium excretion in children with vesicoureteral reflux. Nephrol Dial Transplant 2003; 18: 507–511
[Abstract/Free Full Text] - Papadimitriou A, Nicolaidou P, Garoufi A, Georgouli H, Karpathios T. Hypercalciuria in children with febrile convulsions. Pediatr Int 2001; 43: 231–234[Medline]
- Stapleton FB, Noe HN, Jerkins G, Roy S. Urinary excretion of calcium following an oral calcium loading test in healthy children. Pediatrics 1982; 69: 594–597
[Abstract/Free Full Text]
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