An assessment of dried blood-spot technology for identifying iron deficiency

The present study was undertaken to assess the feasibility of using ferritin and transferrin receptor measurements on dried capillary blood spots to identify iron deficiency (ID) in public health surveys. Measurements on serum and blood spots prepared from venous blood were performed in 71 healthy subjects, 41 of whom were iron-replete and 30 who had ID, either without (n = 20) or with (n = 10) anemia. Parallel measurements were performed on hemolyzed whole blood and washed hemolyzed red blood cells to assess the erythrocyte contribution of ferritin and transferrin receptor to dried blood samples. The concentration of ferritin in dried blood samples was threefold higher than serum assays due to the release of ferritin from hemolyzed erythrocytes, which diminished the usefulness of ferritin measurements for detecting ID. On the other hand, there was negligible erythrocyte contribution to the measurement of transferrin receptor in dried blood spots. The most sensitive parameter in dried blood spots was the ratio of receptor/ferritin, which was suitable for identifying iron-deficiency anemia (IDA), but less reliable than serum assays for detecting milder ID without anemia. We conclude that tandem measurements of serum ferritin and transferrin receptor in dried blood spots can be used to facilitate the identification of IDA in epidemiologic studies.