Serum ferritin and free erythrocyte protoporphyrin in rheumatoid arthritis

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.

Prediction of erosiveness and rate of development of new erosions in early rheumatoid arthritis

Fifty eight patients suffering from a recent onset of rheumatoid arthritis (RA) were studied. Fifty six patients were followed up for 24 months and two for 18 months. Erosions were detected in 17 patients at the onset and at the end of the follow up period the number of patients with erosions was 44. The erosiveness in the joint groups studied was as follows: metatarsophalangeal (MTP) (36 patients), metacarpophalangeal (MCP) (22), proximal interphalangeal (PIP) (21), interphalangeal (IP) joints of first toes and wrists (13), elbows and knees (two), and shoulders, ankles, and hips (one). Erosiveness in the feet was twice that in the fingers, and the erosions in the feet appeared at an earlier phase of disease. Destructions favoured the dominant hand. Swelling in the PIP joints appeared to be a better predictor of erosiveness than joint tenderness. The number of joints to become eroded was significantly increased in the patients with flexor tenosynovitis in the hands. Erythrocyte sedimentation rate (ESR) was more closely related to progression of joint damage than C reactive protein (CRP) or haemoglobin. The rate of development of new erosions was the same in seronegative and seropositive patients. In addition, HLA-DR4 allele did not correlate either with seropositivity or with erosiveness. Adequate antirheumatic drug treatment (gold in most instances) was not able to restrain the erosive process despite decreased rheumatoid disease activity.

Relation between bone erosions and rheumatoid factor IgA and IgM isotypes in recent onset rheumatoid arthritis

In this prospective study 58 patients with early rheumatoid arthritis were followed up for two years with six-monthly assessments including rheumatoid factors (RF) of IgA and IgM subtypes. Initial and mean serum levels of IgA-RFs were raised in patients with an erosive disease course in comparison to non erosive disease. The cases with initially increased serum levels of RFs of both isotypes developed more eroded joints in their hands and feet during the study period than the rest of the patients. None of the differences, however, were statistically significant. Of the tested parameters only clinical rheumatoid activity (Mallya-index) was significantly related to the number of eroded joints during the follow-up. We conclude that serum IgA-type RFs are raised in erosive RA, but the determination of RFs of any kind cannot be used to prognosticate erosiveness.