Serum transferrin receptors in rheumatoid arthritis.
OBJECTIVE--Serum transferrin receptors (sTfR) were determined in patients affected by rheumatoid arthritis (RA) to verify a possible relationship with the degree of anaemia and with the severity of the inflammatory disease. METHODS--sTfR, IL1-b, TNF-a and common parameters of iron metabolism were studied in 72 patients with active RA. Anaemia (Hb < 12 g/dl) was present in 51 patients. Twenty normal healthy subjects and 40 iron-deficient anaemic patients without chronic inflammatory, infective or malignant diseases were studied as controls. RESULTS--In patients with RA sTfR levels were significantly higher than in the normal group but lower than in iron-deficient anaemic patients and correlated positively with ESR and IL1-b and negatively with Hb. Anaemic patients with RA were divided into two groups. Group A (56%) showed a possible iron deficiency (TSI < 16 and ferritin < 50 ng/ml); group B did not show iron deficiency (TSI > 16 and ferritin > 50 ng/ml). No significant difference in sTfR was observed in the two groups. CONCLUSION--sTfR appear to be elevated and related to the degree of anaemia and to the inflammatory process in RA. Reduced sTfR levels in patients with RA compared with patients with iron-deficiency anaemia may indicate a reduced erythropoietic activity in RA.