Serum ferritin and free erythrocyte protoporphyrin in rheumatoid arthritis.

In this prospective study 20 newly diagnosed patients with definite or classical rheumatoid arthritis were followed with serial measurements of serum ferritin and erythrocyte-free protoporphyrin at the beginning of the trial and at 3 and 6 months. The values were correlated with clinical disease activity ad with various laboratory parameters. It was shown that free erythrocyte protoporphyrin has a constant negative correlation with erythrocyte haemoglobin concentration independent of disease activity, while serum ferritin behaves like an acute phase protein. Initial serum ferritin or free erythrocyte protoporphyrin values or their early changes appeared to have no prognostic value as evaluated by the development of new erosions or by the response of the patient to the therapy.