THE DIAGNOSIS OF IRON-DEFICIENCY IN PATIENTS WITH RHEUMATOID-ARTHRITIS AND ANEMIA - AN ALGORITHM USING SIMPLE LABORATORY MEASURES

Objective. Anemia of chronic disorders (ACD) and iron deficiency are c ommon features in rheumatoid arthritis (RA), but may be difficult to d istinguish without marrow sampling, which is invasive, time consuming, and expensive. We sought simple laboratory measures that identified p atients with absent marrow iron stores (iron deficiency). Methods. 45 anemic patients with RA underwent marrow sampling in addition to a com plete blood count and serum ferritin and iron saturation measurements. Results. 47% of patients had iron deficiency. These patients had sign ificantly lower mean corpuscular volume (MCV), serum ferritin, and iro n saturation. A 3 step algorithm was developed using these laboratory variables to identify iron deficiency. This algorithm correctly classi fied 94% patients with iron deficiency and 85% with ACD. Conclusion. O ur study demonstrates that iron deficiency may be reliably identified by measuring serum ferritin, MCV, and iron saturation in many patients with RA, thereby avoiding the trauma and expense of marrow sampling.