Anaemia is a common extra-articular manifestation of rheumatoid arthritis (RA) where anaemia of chronic disease (ACD) and iron deficiency anaemia (IDA) are the two most frequent types. The distinction between these two types of anaemia has always been challenging requiring sophisticated techniques. Serum transferrin receptor (sTfR) a truncated soluble form of the transferrin receptor is one of the parameters that is influenced by the Iron content and supply to the erythrons and is not affected by inflammatory status and therefore the use of the sTfR/log ferritin (sTfR-F) index can be a reliable indicator of functional iron deficiency.
This study aims to evaluate the usefulness of sTfR and sTfR-F index in discriminating the most common types of anaemia in patients with RA.
The study included 50 patients with RA and 30 healthy subjects as a control group. Complete blood picture, C-reactive protein, serum Iron, unsaturated iron binding capacity, sTfR and serum ferritin were tested.
anaemia was present in 34/50 patients; 19 patients had ACD, 9 had ACD/IDA and only 6 patients had IDA. Both the sTfR and the sTfR-F index showed a significant difference between anaemia groups (P values = 0.037 and 0.001, respectively). sTfR-F index has shown to be a very useful parameter that can discriminate efficiently between IDA and ACD and between ACD and ACD/IDA in patients with RA.
