title: Urinary calcium and oxalate excretion in children.
abstract: 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) mumol/mmol], followed by a gradual decrease until 11 years of age [mean 24 (range 6-82) mumol/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) mumol/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).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: First Department of Paediatrics, Semmelweis University Medical School, Budapest, Hungary.
authors.forename: G S
authors.initials: GS
authors.lastname: Reusz
authors.forename: M
authors.initials: M
authors.lastname: Dobos
authors.forename: D
authors.initials: D
authors.lastname: Byrd
authors.forename: P
authors.initials: P
authors.lastname: Sallay
authors.forename: M
authors.initials: M
authors.lastname: Miltényi
authors.forename: T
authors.initials: T
authors.lastname: Tulassay
mesh_terms: D000293:Adolescent; D000375:Aging / Q000378:metabolism; D002118:Calcium / Q000652:urine*; D002648:Child; D002675:Child, Preschool; D002852:Chromatography, Ion Exchange; D003404:Creatinine / Q000652:urine; D005260:Female; D006417:Hematuria / Q000652:urine; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007669:Kidney Calculi / Q000652:urine; D008297:Male; D010070:Oxalates / Q000652:urine*; D012016:Reference Values; D014882:Water-Electrolyte Balance / Q000502:physiology
chemical_list: D010070:Oxalates; D003404:Creatinine; D002118:Calcium