Hematological parameters in preterm infants from birth to 16 weeks of age with reference to iron balance

The objective of this study was to describe the natural kinetics of serum soluble transferrin receptor (S-TfR), ferritin and reticulocyte indices in preterm neonates, and to find out whether these analytes relate to hematocrit (Hct) level in determining the need for red cell (RBC) transfusions.

During a 2-year period, 100 preterm neonates were recruited in a tertiary level neonatal intensive care unit. Inclusion criteria were gestational age < or =34 weeks or birth weight <2000 g. Biochemical markers of iron deficiency and hematological indices were serially analyzed from birth. This report focuses on the first 16 weeks after birth.

The trends of the studied analytes were presented with reference ranges. RBC transfusions did not have a significant effect on reticulocyte hemoglobin content (CHr) or reticulocyte count. Reticulocytes were lowest after the first week and S-TfR at 9 weeks of age. CHr and fraction of immature reticulocytes were highest at birth and decreased thereafter. CHr and reticulocyte count were significantly different in two groups determined by Hct level (Hct < or > or =0.30). This difference was not observed in S-TfR or ferritin concentrations.

In addition to reflecting the activity of erythropoiesis, S-TfR seems to reflect iron balance in preterm neonates. By using CHr and reticulocyte, it is possible to obtain more information about iron balance in relation to erythropoiesis, and it might be useful to combine this information with Hct before making a decision about a transfusion.