Effects of iron supplementation on red blood cell hemoglobin content in pregnancy.

Schoorl M, van der Gaag D, Bartels PC
Hematol Rep 2012;4:e24.
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Review by : C. Breymann
NATA Review

The authors present an interesting study evaluating the effectiveness of iron supplements in late pregnancy. For that purpose, instead of measuring “classic” parameters such as hemoglobin and ferritin concentrations, they introduce newer parameters such as reticulocyte hemoglobin content (HbRet), red cell distribution width (RDW) and zink protoporphyrin (ZPP). These are different analyses based on laser scattergram technology of modern red cell analyzers (RetHb and RDW) and hematofluorometer (ZPP). The authors show that after 4 weeks of oral iron supplementation the RetHb content improved significantly, as did the RetHb/RBC-Hb ratio. Also the RDW increased, indicating freshly produced red cells with normal Hb content. As expected, also mean Hb levels improved significantly. ZPP did not show significant changes.

We and others have presented data on RetHb and RDW in recent publications (Fetal Diagn Ther 2009;25:239–245; Blood Cells Mol Dis 2002;29:506-16; Acta Obstet Gynecol Scand 2000;79:720-2). It was found that RetHb content is a sensitive marker of red cell hemoglobin changes. It is interesting to note that, in the 2009 study, we found decreased RetHb content only in women with Hb levels < 9 g/dL, i.e. severe anemia, while all women had decreased ferritin and increased serum transferrin receptor levels. In the study by Schoorl et al., mean RetHb decreased in women with Hb > 10 g/dL, but no data are presented concerning classic iron parameters (ferritin, sTfR etc.). It would have been of interest to see the data for variables like ferritin and sTfR levels in the same patients and to compare their course with the proposed parameters.

It should be noted that modern red cell analyzers are not available in many laboratories and/or poorer countries. Here we have to stick with “classic” and easy available parameters such as hemoglobin and ferritin. Chosing a hemoglobin cutoff for the diagnosis of anemia of 10.5 g/dL and lower will decrease the number of women who receive iron just because of physiological anemia, since the suggested fith percentile of anemia due to hemodilution lies around 10.5 g/dL. Values below this level should be regarded as true anemia at any trimester. Finally , we are concerned that the authors start iron treatment only at last trimester. During pregnancy, I think it makes more sense to evaluate the suggested parameters early on and to start iron supplements at an early (first trimester) stage. This is because iron will surely be needed before the end of pregnancy for the mother’s and the fetus’ sake.

– Christian Breymann