Erythropoietic activity and soluble transferrin receptor level in neonates and maternal blood

Serum transferrin receptor (sTfR) concentration reflects functional iron status and erythropoietic activity. The aims of this study were to examine gender differences of erythropoiesis in newborns and to evaluate the influences of maternal anaemia or iron deficiency on foetal cord blood parameters for iron status and sTfR. In total, 527 newborns and their mothers were examined. Reticulocytes were analysed by flow cytometry and sTfR was measured by an immunoenzymometric method. There were no sex differences in haematological or iron parameters. However, the reticulocyte maturity index (RMI) of male neonates was 37.45%, significantly higher than the 26.81% in female neonates (p <0.01). The high fluorescence reticulocytes (HFR) and middle fluorescence reticulocytes (MFR) of male neonates were 4.91% and 22.36%, respectively, while those of female neonates were 3.31% and 17.83%, respectively (p < 0.01 for each gender). The sTfR concentrations of male and female neonates were 6.27 mg/l and 5.09 mg/l, respectively (p < 0.01). Values for serum iron, ferritin and reticulocyte subpopulations were significantly lower in the newborns of anaemic mothers. However, newborns of iron-deficient mothers showed no differences in iron parameters from those of non-iron-deficient mothers.

The higher values of RMI and sTfR observed in male neonates indicate that erythropoietic activity is higher in this group. Iron transport to the foetus appears to be independent of maternal iron deficiency. However, iron transport and erythropoiesis in newborns seems to decline from the time that the mothers acquire frank iron deficiency anaemia.