Single values of serum transferrin receptor and transferrin receptor ferritin index can be used to detect true and functional iron deficiency in rheumatoid arthritis patients with anemia.

OBJECTIVE

To elucidate the use of serum transferrin receptor (sTfR) to distinguish between iron-deficiency anemia (IDA) and anemia of chronic disease (ACD), and to establish an improved scheme to identify functional iron deficiency (FID) in rheumatoid arthritis (RA) patients with anemia.

METHODS

We studied 30 anemic RA patients whose iron status was confirmed by bone marrow examination and determination of the sTfR level, serum ferritin level, and sTfR-log ferritin index (TfR-F Index). All patients with diminished or exhausted iron stores (n = 18) received oral iron supplementation.

RESULTS

Baseline values of sTfR and the TfR-F Index predicted the response correctly in all patients who received supplementation treatment and were normal in 10 of 11 patients with normal initial iron stores (ACD).

CONCLUSION

The results of this study elucidate the roles of sTfR and the TfR-F Index in the differential diagnosis between IDA and ACD and provide direct evidence that these parameters are useful in detecting FID, irrespective of the concurrent iron storage status.