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Hypercalciuria in children with urolithiasis
Insights
Idiopathic renal hypercalciuria and absorptive hypercalciuria are common in children with urolithiasis. Metabolic evaluation is crucial for diagnosing these urinary calcium excretion disorders in pediatric kidney stone patients.
Area of Science:
- Pediatric Nephrology
- Urology
- Metabolic Disorders
Background:
- The causes of kidney stones in children are not fully understood.
- Idiopathic renal hypercalciuria and absorptive hypercalciuria are potential contributors to pediatric urolithiasis.
Purpose of the Study:
- To investigate the prevalence and roles of renal and absorptive hypercalciuria in children with unexplained urolithiasis.
- To determine the necessity of detailed metabolic assessments in pediatric kidney stone disease.
Main Methods:
- Performed oral calcium loading studies in 21 children with calcareous urolithiasis.
- Measured urinary calcium-to-creatinine (UCa/UCr) ratios before and after calcium load.
- Assessed serum parathyroid hormone levels.
Main Results:
- Renal hypercalciuria identified in 13 children (fasting UCa/UCr > 0.21).
- Absorptive hypercalciuria identified in 4 children (normal fasting UCa/UCr, elevated post-load UCa/UCr).
- Normal urinary calcium excretion in 4 patients; normal parathyroid hormone in all hypercalciuric children.
Conclusions:
- Hypercalciuria is frequently observed in children with kidney stones.
- Detailed metabolic evaluation is warranted for pediatric patients diagnosed with urolithiasis.
Abstract:
The pathogenetic roles of idiopathic renal hypercalciuria and absorptive hypercalciuria in children with urolithiasis have not yet been determined. Oral calcium loading studies were performed in 21 children with unexplained calcareous urolithiasis. Thirteen children, aged 20 months to 17 years, were found to have renal hypercalciuria after an overnight fast (urinary calcium-urinary creatinine [UCa/UCr] ratio in milligrams, greater than 0.21). Four children were found to have absorptive hypercalciuria. In this group, fasting UCa/UCr values were normal (SEM, 0.12 +/- 0.02); however, UCa/UCr values were elevated (SEM, 0.31 +/- 0.01) after the oral calcium load. Serum parathyroid hormone values were normal in all children with hypercalciuria. Urinary calcium excretion was normal in four patients. These data indicate that hypercalciuria may frequently occur in children with urolithiasis and that detailed metabolic evaluation is warranted in children with kidney stone disease.