Persistent anemia and hypoalbuminemia in rheumatoid arthritis patients with low serum triiodothyronine level

Objectives: To determine the clinical characteristics of rheumatoid arthritis (RA) patients with low serum triiodothyronine (T3) levels. Methods: We evaluated serum free T3 (fT3), free T4, and thyroid-stimulating hormone (TSH) levels in 338 RA patients. After excluding patients taking anti-thyroid drugs or having anti-thyroid antibodies, we compared the clinical characteristics of the RA patients with low fT3 to those with normal/high fT3, before and after RA treatment. Results: Six percent of RA patients had low fT3 levels. Patients with low fT3 were older and had higher disease activity scores (DAS28), higher Steinbrocker stage, higher health assessment questionnaire scores, lower body mass index, and lower hemoglobin and albumin levels compared with normal/high-fT3 patients. After RA treatment, fT3 levels normalized in half of the low-fT3 patients and remained low in the other half. Although DAS28 scores were similarly improved in both subgroups of the low-fT3 patients, anemia and hypoalbuminemia did not normalize in the persistently low-fT3 subgroup. Conclusion: Low serum fT3 levels represent the profound wasting seen in RA patients that is characterized by anemia and hypoalbuminemia and that cannot be evaluated by DAS28 scores alone.