Urine risk factors in children with calcium kidney stones and their siblings

Kidney Int. 2012 Jun;81(11):1140-8. doi: 10.1038/ki.2012.7. Epub 2012 Feb 22.


Calcium nephrolithiasis in children is increasing in prevalence and tends to be recurrent. Although children have a lower incidence of nephrolithiasis than adults, its etiology in children is less well understood; hence, treatments targeted for adults may not be optimal in children. To better understand metabolic abnormalities in stone-forming children, we compared chemical measurements and the crystallization properties of 24-h urine collections from 129 stone formers matched to 105 non-stone-forming siblings and 183 normal, healthy children with no family history of stones, all aged 6 to 17 years. The principal risk factor for calcium stone formation was hypercalciuria. Stone formers have strikingly higher calcium excretion along with high supersaturation for calcium oxalate and calcium phosphate, and a reduced distance between the upper limit of metastability and supersaturation for calcium phosphate, indicating increased risk of calcium phosphate crystallization. Other differences in urine chemistry that exist between adult stone formers and normal individuals such as hyperoxaluria, hypocitraturia, abnormal urine pH, and low urine volume were not found in these children. Hence, hypercalciuria and a reduction in the gap between calcium phosphate upper limit of metastability and supersaturation are crucial determinants of stone risk. This highlights the importance of managing hypercalciuria in children with calcium stones.

Publication types

  • Multicenter Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adolescent
  • Age Factors
  • Biomarkers / blood
  • Calcium / urine*
  • Calcium Oxalate / urine*
  • Calcium Phosphates / urine*
  • Case-Control Studies
  • Child
  • Crystallization
  • Female
  • Genetic Predisposition to Disease
  • Humans
  • Hypercalciuria / complications*
  • Hypercalciuria / genetics
  • Hypercalciuria / urine
  • Kidney Calculi / etiology*
  • Kidney Calculi / genetics
  • Kidney Calculi / urine
  • Linear Models
  • Male
  • Risk Assessment
  • Risk Factors
  • Siblings*
  • United States


  • Biomarkers
  • Calcium Phosphates
  • Calcium Oxalate
  • calcium phosphate
  • Calcium