Serum transferrin receptor-ferritin index shows concomitant iron deficiency anemia and anemia of chronic disease is common in patients with rheumatoid arthritis in north India

Anemia is a frequent cause of morbidity in patients with rheumatoid arthritis (RA). We studied the prevalence of anemia of chronic disorders (ACD) and ACD with coexistent iron deficiency anemia (IDA) in patients with RA using sTfR/log ferritin ratio (sTfR - F index). Complete blood counts, percent transferrin saturation, serum ferritin, sTfR, sTfR-F index measurements were carried out in 100 anemic RA patients. Twenty-five IDA subjects without any other illness and 25 age- and sex-matched normal controls were studied. Prevalence of anemia in RA patients was 50.5%. Patients with sTfR-F index value 1.5 were classified as ACD with coexistent IDA. Using these criteria, 20% patients were found to have pure ACD and 80% patients had coexistent ACD and IDA. In the normal control group, sTfR-F index was found to be 0.16-1.8. We found that sTfR-F index can clearly distinguish IDA control cases and normal subjects with no overlap in the range of sTfR-F index.