The use of serum ferritin estimation in the investigation of anaemia in patients with rheumatoid arthritis

Abstract

We report a retrospective study of 101 patients with rheumatoid arthritis and anaemia undergoing investigation in a teaching hospital rheumatology unit. Patients with anaemia of chronic disorder had significantly higher serum ferritin (p < 0.0001), mean corpuscular volume (p < 0.05), and acute phase reactants (p < 0.001). The sensitivity, predictive value and validity of measuring serum ferritin to predict the absence of bone marrow iron stores was studied. Maximum validity (89%) was achieved by defining iron deficiency as occurring when serum ferritin was < 75 ng/ml. 93% of patients with ferritin < 50 ng/ml were iron deficient on bone marrow examination. 91% of patients with ferritin > 100 ng/ml were iron replete on bone marrow examination. 86% of patients had ferritin < 50 or > 100 ng/ml. Age was not a significant confounding factor. Serum ferritin concentration is an informative investigation in rheumatoid patients with anaemia. Correct interpretation of the results eliminates the need for bone marrow aspiration in the majority of cases.