Anemia of chronic disorders (ACD) and iron deficiency are common features in rheumatoid arthritis (RA), but may be difficult to distinguish without marrow sampling, which is invasive, time consuming, and expensive. We sought simple laboratory measures that identified patients with absent marrow iron stores (iron deficiency).
45 anemic patients with RA underwent marrow sampling in addition to a complete blood count and serum ferritin and iron saturation measurements.
47% of patients had iron deficiency. These patients had significantly lower mean corpuscular volume (MCV), serum ferritin, and iron saturation. A 3 step algorithm was developed using these laboratory variables to identify iron deficiency. This algorithm correctly classified 94% patients with iron deficiency and 85% with ACD.
Our 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.