The role of serum transferrin receptor in the diagnosis of iron deficiency

Background and Objective. Iron deficiency anemia (IDA) is often associated with inflammatory disorders. The most conventional parameters of iron metab olism are therefore affected, making the evaluation of iron status difficul t. Serum transferrin receptor (sTfR) levels are raised in iron deficiency b ut are not influenced by inflammatory changes. The aim of this study was to investigate the role of sTfR in differentiating IDA with inflammatory feat ures. Design and Methods. A diagnostic study of sTfR measured by immunoassay was carried out in IDA and anemia of chronic disorders (ACD). The cut-off point s of sTfR and the ratio of sTfR/serum ferritin, which were obtained after c omparing IDA and ACD, were applied to a group of 64 patients with mixed iro n patterns (MIX) (16 with ACD and 48 with IDA). Results. The best cut-off point of sTfR between IDA and ACD was 4.7 mg/L. A pplying this cut-off to the MIX group, an efficiency of 87% was obtained (s ensitivity 92% and specificity 81%). This level of sTfR correctly classifie d 53 out of 64 cases of the MIX group (83%). Using the ratio of sTfRx 100/s erum ferritin, the best cut-off point was 8 (efficiency 100%), which correc tly classified 62 out of 64 cases of the MIX group (97%). Interpretation and Conclusions. This study demonstrates that sTfR in conjun ction with other iron parameters is very useful in iron deficiency evaluati on, especially in hospital practice. Iron treatment should be considered in patients with mixed patterns of iron status, in which the diagnosis of IDA versus ACD is difficult, when the levels of sTfR exceed the cut-off point. (C)1998, Ferrata Storti Foundation.