Serum transferrin receptor: a specific marker of iron deficiency in pregnancy

Background: Current markers of iron deficiency tend to be less reliable in pregnancy. Objective: Our aim was to study the usefulness of soluble serum transferrin receptor (sTfR) as a marker for iron deficiency during early and late gest ation and to define iron status in 254 pregnant Swedish women. Design: We performed a cross-sectional and longitudinal evaluation of sTfR in comparison with concentrations of serum ferritin and hemoglobin in blood collected around gestational weeks 11 and 36, Results: The specificity of sTfR was 100%, The sensitivity in relation to b oth anemia and depleted iron stores was approximate to 70%, but this figure is less reliable because of few samples. sTfR in early pregnancy was low: 11% of women had a value below the reference interval. sTfR increased signi ficantly from early to late pregnancy even in the group of women with persi sting iron stores. In late pregnancy, 14% of women developed tissue iron de ficiency and 5% had iron deficiency according to a combination of all 3 mar kers. Conclusions: sTfR seems to be a specific and sensitive marker of iron defic iency in pregnancy and may have advantages over serum ferritin and hemoglob in. The low sTfR concentration in early gestation seems to be caused by red uced erythropoiesis, whereas the increase from early to late pregnancy refl ects increased erythropoiesis, and in case of iron deficiency, also tissue iron deficiency. Further studies are needed to verify whether decreased ery thropoiesis reduces the possibility of detecting iron deficiency during ear ly gestation by sTfR.