The Importance of Log Ferritin and Transferrin /Log Ferritin in Differentiating Iron Deficiency Anemia from Anemia of Chronic Disease in Rheumatoid Arthritis Patients.

The most common types of anemia in rheumatoid arthritis (RA) are iron deficiency anemia (IDA) and anemia of chronic disease (ACD).The differentiation between both is important and challenging. Our objective is to select the most accurate method that differentiates IDA from ACD in RA patients. This case control study was carried out on 80 RA patients. 40 RA patients with anemia and 40 RA patients without anemia, complete blood count, assessment of disease activity using DAS 28 score, serum iron, transferrin level, transferrin saturation (TSAT), serum ferritin, log ferritin and transferrin /log ferritin were tested, anemic patients were divided into 2 subgroups according to TSAT: group Ia (with low TSAT) and group Ib (with normal TSAT). There was a statistically significant difference between anemic and non-anemic RA patients as regard serum iron level and transferrin saturation. Among the anemic group 67.5% had low TSAT (IDA) and 32.5% had normal TSAT (ACD). In these 2 subgroups there was no significant differences as regard DAS28 score, blood indices, serum ferritin and transferrin /log ferritin) and there was a positive correlation between TSAT and ferritin and log ferritin and a significant negative correlation between TSAT and transferrin/log ferritin. In conclusions, Iron deficiency anemia is prevalent in RA patients. A combination of serum ferritin and TSAT is simple and accurate parameter to differentiate both. Log ferritin and transferrin /log ferritin may be promising new parameters in diagnosis of IDA in general population but their use in inflammatory diseases like RA still has a limitation.