Biologic variation in electrolytes and essential microelements in the blood of neonates and their mothers

Serum concentration and biological variability (CVB%) of total calcium (Ca) magnesium (Mg), iron (Fe), zinc (Zn) and copper (Cu) were determined in 22 sera of maternal and umbilical cord blood in normal pregnancies. The concentrations of Ca (2.48 +/- 0.13 vs 2.27 +/- 0.13 mmol/l), Mg (0.84 +/- 0.06 vs 0.80 +/- 0.07 mmol/l), Fe (24.1 +/- 6.62 vs 10.7 +/- 4.94 mumol/l) and Zn (14.1 +/- 1.78 vs 9.1 +/- 2.21 mumol/l) in the cord sera were significantly higher than in maternal sera (p < 0.01), whereas maternal copper concentrations (36.6 +/- 4.82 vs 9.2 +/- 2.21 mumol/l), were significantly higher than in cord sera (p < 0.01). Biological variability of Ca (5.37 vs 4.84%), Mg (8.39 vs 6.69%), Fe (46.1 vs 27.3%) and Zn (24.1 vs 12.3%) values was higher in the maternal sera than the respective values in the cord sera, while the biological variability of copper in the cord sera was significantly higher than the respective value in the maternal sera (26.7 vs 12.8%). These results are in agreement with those previously reported and suggest that fetal homeostasis of Ca, Mg, Fe and Zn is at least partly independent of maternal factors.