Urinary Magnesium, Calcium, and Phosphorus to Creatinine Ratios of Healthy Elementary School Lebanese Children

Abstract

Urinary magnesium (Mg), calcium (Ca), and phosphorus (P) excretions are known to vary greatly between populations due to dietary habits, physical activity, mineral content of water, climate, genetics, and race. Thus, it is essential to determine the normal values in each population in order to assess the status as well as to diagnose any possible abnormality of metabolisms especially hypercalciuria. A study was conducted to determine urinary Mg/creatinine (Cr), Ca/Cr, and P/Cr ratios of healthy Lebanese elementary schoolchildren. Using a multi-stage cluster sampling at district, school, and class levels, a sample of 1403 children (781 boys and 622 girls), from 26 different schools, was selected. Non-fasting morning urine samples and anthropometric data were collected and analyzed. The mean Mg/Cr, Ca/Cr, and P/Cr ratios were 0.122 ± 0.075 mg/mg (0.568 ± 0.348 mM/mM), 0.084 ± 0.101 mg/mg (0.237 ± 0.286 mM/mM), and 0.692 ± 0.417 mg/mg (2.527 ± 1.524 mM/mM), respectively, with no significant difference between boys and girls (P = 0.706, 0.161, and 0.604; respectively). The 95th percentile of Mg/Cr, Ca/Cr, and P/Cr ratios fluctuated with age, showing a sharp decrease in Ca/Cr and P/Cr at the age of 10. The mean Mg/Cr, Ca/Cr, and P/Cr ratios were comparable to those of similar age groups in other populations. The 95th percentiles of Mg/Cr, Ca/Cr, and P/Cr ratios were 0.26 mg/mg (1.23 mM/mM), 0.27 mg/mg (0.76 mM/mM), and 1.48 mg/mg (5.40 mM/mM), respectively. These values can be used as cutoffs to detect abnormalities in these three minerals' metabolisms among healthy Lebanese children.

Reference range of random urinary calcium creatinine ratio in North Indian children and adolescents

“…The overall mean UCaCrR of 0.0530±0.0368 was significantly lower than values reported from different geographic regions such as Turkey, Lebanon, Iran, Italy, and Argentina, 5,8,10,13,23,24,27,36) including a report from India where the reported mean was 0.10±0.094. 29) The 95th percentile of UCaCrR in the present study was 0.14 and ranged from 0.10-0.20 among different age groups.…”

“…[12][13][14] Since there is wide variation in UCaCrR values among various geographic regions, reference ranges and 95th percentile values specific for each population are needed. [4][5][6][7][8][9][10][14][15][16][17][18][19][20][21][22][23][24][25][26][27] In the present study, we report normative data of UCaCrR in healthy North Indian children and adolescents.…”

“…1,2) Calcium excretion depends on age, race, dietary habits, vitamin D status, renal function, and various genetic factors. [3][4][5][6][7][8][9][10] Normal calcium excretion and urinary calcium creatinine ratio (UCaCrR) cutoff values to define hypercalciuria vary in different age groups and by region. Hypercalciuria has been defined as daily urinary excretion of more than 4 mg calcium/kg body weight if a child is over 2 years old.…”

“…[16][17][18][19] UCaCrR requires a reference range for different races and geographic regions. 1,3) Reference ranges for various regions and ethnic backgrounds are available in the literature, [4][5][6][7][8][9][10][17][18][19][20][21][22][23][24][25][26][27] but data from India is sparse. 28,29) In addition, none of these published studies have accounted for the dietary intake of calcium and serum 25-hydroxy-vitamin D (25OHD) levels, which likely affect UCaCrR.…”

Reference intervals of spot urine copper excretion in preschool children and potential application in pre-symptomatic screening of Wilson’s disease

“…Our long-term interest in nutritional research and biomarker studies provided us an insight into the application of spot urine as biomarkers (11,16). In the past, we pioneered the use of spot urine magnesium as a biomarker for assessment of body status of magnesium (11) and it had been used in both clinical and research settings (17,18). There were other groups which carried out pilot studies in the use of spot urine in assessment of body status or dietary intake of sodium (19–21), magnesium and other trace elements (22,23).…”