Iron body stores in patients treated with red-cell transfusions
Abstract
Background: Consequence of chronic transfusion therapy is a secondary iron overload, which adversely affects the heart, liver and endocrine glands. This can be minimized by iron chelating therapy. The assessment of iron overload is essential to assign and adjust this treatment. Serum ferritin is a widely used marker for the estimation of iron stores. However, a variety of conditions alter the relationship between serum ferritin levels and body iron stores. Soluble transferrin receptors in serum (sTfR) reflect the degree of erythropoiesis and the status of body iron. The data on usage of serum transferrin receptors for the assessment of iron overload are sparse. The purpose of our work was to estimate iron overload in transfusion dependent patients and to assess the combinative value of serum transferrin receptors and ferritin in prediction of iron load.
Methods: Serum levels of iron, transferrin saturation, ferritin and sTfR were evaluated for 36 transfusion dependent patients. Twenty of them had myelodysplastic syndrome (MDS). Body iron (mg/kg) was calculated from the sTfR/ferritin ratio with the use of regression formula developed by Cook et al. Levels of serum parameters and calculated body iron were compared with estimated iron overload. We used absolute number of transfused units of blood as a measure of iron overload.
Results: Serum ferritin above 1000 ug/L and above 2000 ug/L was found in 69 % and in 47 % of transfusion dependent patients. For MDS patients these levels were found in 85 % and 65 %. Concentration of sTfR was lower in the group of patients than it was in control group of healthy people (p = 0.001). We found a significant inverse correlation between sTfR and transferrin saturation. The estimated iron overload correlates well with serum ferritin (ñ = 0.66, p < 0.01) and calculated body iron (ñ = 0.53, p < 0.01).
Conclusions: Patients on chronic transfusion therapy with ferritin > 1000 ug/L and good prognosis (subgroup of MDS) should need intensification of chelating treatment. In this study we didn’t find any advantages of calculating body iron in comparison to measuring serum ferritin levels for the estimation of iron overload.
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