Urinary calcium and oxalate excretion in children
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We have established normal values for calcium/creatinine (Ca/Cr) and oxalate/creatinine (Ox/Cr) ratios in 25 infants (aged 1–7 days) and 391 children (aged 1 month to 14.5 years) and compared these with values obtained in 137 children with post-glomerular haematuria and 27 with nephrolithiasis. Oxalate was measured by ion chromatography. Nomograms of Marshall and Robertson were used to calculate urine saturation to calcium oxalate. The Ca/Cr ratio was normally distributed whereas the Ox/Cr ratio had a log-normal distribution. The molar ratio of Ca/Cr was the lowest in the first days of life and the highest between 7 month and 1.5 years (mean±SD=0.39±0.28 mmol/mmol). Following a slight decrease it stabilised by the age of 6 years (0.34±0.19 mmol/mmol). The highest Ox/Cr values were measured during the 1st month of life [geometric mean 133 (range 61–280) μmol/mmol], followed by a gradual decrease until 11 years of age [mean 24 (range 6–82) μmol/mmol]. Thirty-six haematuric children had hypercalciuria (26%), 23 had absorptive hypercalciuria, 13 renal type. Children with absorptive hypercalciuria on a calcium-restricted diet had significantly higher oxalate excretion than those with renal hypercalciuria and the control group [38 (range 28–49) vs. 22 (range 16–29) and 23 (range 22–27) μmol/mol respectively,P<0.01]. Calcium oxalate urine saturation of stone patients was higher than that of patients with haematuria and the normal population (1.18±0.05 vs. 1.06±0.03,P<0.03 and 0.84±0.03,P<0.001 respectively). The measurement of Ca/Cr and Ox/Cr in first-morning urine samples is suitable for screening for hypercalciuria and hyperoxaluria. Interpretation of the values requires age-specific reference values. Both calcium and oxalate determinations should be part of the evaluation of patients with haematuria, hypercalciuria or nephrolithiasis.
Key wordsCalcium Oxalate Normal values Nephrolithiasis
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- 1.Malek RS, Kelalis PP (1976) Pediatric urolithiasis. J Urol 113: 545–550Google Scholar
- 14.Small H, Stevens T, Baumann W (1975) Novel ion exchange chromatographic method using conductimetric method. Anal Chem 47: 1801–1810Google Scholar
- 19.Reusz GS, Tulassay T, Miltényi M (1988) Differentiation of glomerular and non-glomerular haematuria. Lancet II: 50–51Google Scholar
- 20.Schnackenburg C, Byrd DJ, Latta K, Reusz GS, Graf D, Brodehl J (1994) Determination of oxalate excretion in spot urines of healthy children by ion chromatography. Eur J Chem Clin Biochem 32: 27–29Google Scholar
- 35.Lalau JD, Achard JM, Bataille P, Bergot C, Jans I, Boudailliez B, Petit-J, Henon G, Westeel PF, Esper N el, et al (1992) Densite vertebrale des lithiasiques hypercalciuriques. Sa relation avec les apports calciques et proteiques et le metabolisme de la vitamine D. Ann Med Interne (Paris) 143: 293–298Google Scholar