The correlation between ferritin level and acute phase parameters in rheumatoid arthritis and systemic lupus erythematosus

Objective: In this study, we evaluated the relationship between ferritin levels and disease activation in rheumatoid arthritis (RA) patients.

Material and Methods: We included 44 patients with RA, 20 patients with systemic lupus erythematosus (SLE), 25 patients with infection, 22 patients with malignancy, and 20 healthy control subjects. Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), whole blood count, and serum iron parameters were determined in all cases. The joint findings in RA patients were recorded, and disease activity score (DAS) was calculated. In SLE patients, antinuclear antibody (ANA) and anti-dsDNA titers and C3 and C4 complement levels were determined. SLE disease activity index (SLEDAI) score was calculated.

Results: Serum ferritin levels in the RA, SLE, and control groups were lower than those in the infection and malignancy groups (p<0.05). The ferritin levels in the RA group did not differ significantly from the SLE and control groups. In RA patients, serum ferritin level had a positive correlation with ESR, CRP, RF, platelet count, and DAS score and had a negative correlation with hematocrit (all p values <0.05). In SLE patients, on the other hand, serum ferritin had a positive correlation with ANA, anti-dsDNA, and SLEDAI (all p values <0.05). According to DAS, ferritin level in inactive RA patients was lower than that in active RA patients. When transferrin saturation was considered, iron deficiency anemia was a quite frequent finding in both active and inactive RA patients.

Conclusion: Interestingly, we observed that ferritin level in RA patients was similar to the control group; however, it was a good parameter of disease activation. This is because a reduction in storage iron and resultant iron deficiency anemia are very common in RA patients.