THE RELATIONSHIP OF HAEMOGLOBIN TO SERUM ERYTHROPOIETIN CONCENTRATIONS IN THE ANAEMIA OF RHEUMATOID ARTHRITIS: THE EFFECT OF ORAL PREDNISOLONE

Previous studies of the erythropoietin response to anaemia inRA have yielded conflicting findings. Some have found the responseto be impaired and others have found a normal response. We havecompared erythropoietin (EPO) levels measured by radioimmunoassay,in 54 anaemic rheumatoid patients and 55 patients with irondeficiency anaemia but no inflammatory disease. The erythropoietin response in the rheumatoid patients was impairedcompared with the control group (P < 0.025) but only sevenrheumatoid patients showed a response which fell below the 95%confidence intervals predicted for the control group. Rheumatoidpatients who fell within the highest quartile for serum ferritinconcentrations (i.e. those most likely to have anaemia of chronicdisease) had significantly lower EPO levels compared with thecontrol group (P < 0.01). EPO levels in rheumatoid patientswithin the lowest quartile for ferritin (i.e. those with irondeficiency anaemia) were not significantly different from thecontrol group (P = 0.670). The difference in EPO response betweenthe RA patients in the upper and lower quartile for ferritinapproached but did not achieve significance (P = 0.056). Ina second study 15 anaemic RA patients were given a 5-day courseof oral prednisolone 1.5 mgkg^-1. Haemoglobin did not rise significantlyuntil day 4 but EPO levels fell by day 1 (P < 0.005) andremained lower than pretreatment values throughout the study.Thus, in RA patients, anaemia of chronic disease is associatedwith inappropriately low EPO concentrations but this does notappear to be the major cause of the anaemia and Hb responseto prednisolone does not depend upon an increase in EPO concentration. KEY WORDS: Rheumatoid arthritis, Anaemia of chronic disease, Erythropoietin, Prednisolone