Effects of iron supplementation on microcytic and hypochromic red blood cells during the third trimester of pregnancy.

INTRODUCTION

Mild anaemia often occurs in the third trimester of pregnancy. Particularly in the Hb range between 101-110 g/L it is difficult to determine whether the decreased haemoglobin concentration is physiological or pathological and whether supplementation is required. The aim of this study was to gain insight into the added value of measuring the percentages of microcytic RBCs (%MicroR) and hypochromic RBCs (%Hypo-He) for monitoring effects of iron supplementation in case of suspected iron-deficient erythropoiesis (IDE) in the third trimester of pregnancy.

METHODS

After assessing haematological parameters and zinc protoporphyrin/heme ratio as marker for IDE, subjects were classified into a group with symptoms of IDE (n = 39) or without IDE (n = 106). The subjects with IDE (n = 39) were treated with iron supplementation. After 4 weeks effects of treatment were evaluated.

RESULTS

In the group of pregnant women with IDE results of %MicroR and %Hypo-He were increased (p = <.001), compared to the group without haematological symptoms of IDE, whereas RET-He, RBC-He and delta-He were decreased (p = <.001). A significant positive correlation to increased values of %MicroR (r = .75, p = <.001) and %Hypo-He (r = .77, p = <.001) with ZPP was established. However, in the ZPP interval 75-100 μmol/mol heme a slight overlap was demonstrated between subjects with and without symptoms of IDE. After iron supplementation, %Hypo-He decreased (p = .002) while %MicroR remained stable. RET-He, delta-He and RDW-SD increased (p = <.001).

CONCLUSION

The added value of %MicroR and %Hypo-He as a single marker for IDE is poor. However, combined interpretation of %MicroR, %Hypo-He, Ret-He and delta-He has added value in monitoring erythropoiesis during pregnancy.