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[Normal values of calcium and oxalate excretion in children]
Insights
Establishing normal calcium/creatinine and oxalate/creatinine ratios in children is crucial for diagnosing hypercalciuria and hyperoxaluria. Age-specific reference values are essential for accurate interpretation in pediatric urine screening.
Area of Science:
- Pediatric Nephrology
- Clinical Chemistry
Context:
- Accurate reference ranges for urinary calcium/creatinine (Ca/cr) and oxalate/creatinine (Ox/cr) ratios are vital for diagnosing kidney conditions in children.
- Previous studies have lacked comprehensive age-specific data for these crucial biomarkers in pediatric populations.
Purpose:
- To establish age-specific normal reference values for urinary Ca/cr and Ox/cr ratios in a cohort of healthy infants and children.
- To determine the suitability of first morning urine samples for screening hypercalciuria and hyperoxaluria in pediatric patients.
Summary:
- Analyzed urine samples from 416 healthy children (1 day to 14.5 years) using ion-chromatography for oxalate measurement.
- Found that urinary Ca/cr ratios peak between 7 months and 1.5 years, while Ox/cr ratios are highest in the first month of life, with both decreasing with age.
- Established age-dependent reference ranges, highlighting the need for age stratification in interpreting results.
Impact:
- Provides essential age-specific reference values for pediatric Ca/cr and Ox/cr, aiding in the diagnosis of hypercalciuria and hyperoxaluria.
- Supports the use of first morning urine samples for effective screening of these conditions in children.
- Informs clinical evaluation of pediatric patients presenting with hematuria, hypercalciuria, or nephrolithiasis, improving diagnostic accuracy.
Abstract:
Aim of the study was to establish normal values for calcium/creatinine (Ca/cr) and oxalate/creatinine (Ox/cr) ratio in infants and children. Urine probes of 416 healthy children (25 infants aged 1-7 days and 391 children aged 1 month-14.5 years) were analysed. Oxalate was measured by ion-chromatography. Urinary Ca2+/cr was normally distributed, Ox/cr had log-normal distribution. Ca/cr was the lowest in the first days of life, the highest between 7 month-1.5 years (mean +/- SD = 0.39 +/- 0.28 mmol/mmol), a slight decrease could be observed until 14 years (0.34 +/- 0.18). The highest Ox/cr values were measured during the first month of life (geometric mean/range/ = 133 /61-280 mmol/mmol/), followed by gradual decrease until 14 years (25/6-73/). The measurement of Ca2+/cr and Ox/cr in first morning urine samples is suitable for screening of hypercalciuria and hyperoxaluria. The interpretation of the values requires age specific reference values. Both calcium and oxalate determinations should be the part of the evaluation of patients with hematuria, hypercalciuria or nephrolithiasis.