CAUSES OF NEPHROCALCINOSIS IN CHILDREN REFERRING TO CHILDREN'S HOSPITAL OF TABRIZ

Nephrocalcinosis is defined as calcium deposition in renal parenchyma. Etiology of nephrocalcinosis varies depending on geographic and genetic conditions, age of study population and methods of different studies. The aim of this study is to evaluate the etiology of nephrocalcinosis in children's Hospital of Tabriz.

Materials & Methods: In this descriptive study, the profiles of 62 children with ultrasound diagnosis of nephrocalcinosis in Children's Hospital of Tabriz during the last 10 years (1999-2009) were reviewed. Patients’ demographics, clinical and laboratory findings, underlying etiology of nephrocalcinosis and outcome were documented.

Results: The mean age at presentation was 23.4±36.2 months (1 month to 12 years). Thirty five (56.4%) patients were male and 27 patients (43.6%) were female. Failure to thrive was found in 54.8%, polyuria in 48.4% and polydipsia in 45.2% of patients. The most frequent underlying causes of nephrocalcinosis were distal renal tubular acidosis (30.6%), hypervitaminosis D (16%), medullary sponge kidney (8%), hyperoxaluria (8%) and bartter syndrome (6.5%). The cause of nephocalcinosis remained unknown in 6.5% of the cases. At the end of follow-up period 48 patients (77.4%) had normal glomerular filtration rate and 13 patients (20.9%) had decreased GFR that 4 of them (with diagnosis of hyperoxalluria) progressed to end-stage renal disease. One patient (1.6%) with barter syndrome died.

Conclusion: Demographic features and etiologies of nephrocalcinosis in this study are similar to the other studies. While in comparison with literature, rate of GFR reduction is higher at the end of follow up period.