Relation between Thyroid Function and Serum Interleukins-6 and - 10 in Systemic Lupus Erythematosus and Rheumatoid Arthritis

Alterations in the circulating thyroid hormone concentrations constituting the euthyroid sick syndrome (ESS) is frequently associated with systemic non-thyroidal diseases such as a systemic connective tissue disease (SCTD). Aim: to elucidate the possible relation between interleukins (IL6 and IL-10) and any changes in thyroid hormone level in patients with SCTD. Subjects and Methods: Thirty patients with systemic lupus erythematosus (SLE) and thirty rheumatoid arthritis (RA) patients in addition to 30 healthy age- and sex- matched controls were recruited from the Internal Medicine Department of Ain Shams University Hospital. Serum level of IL-6 and IL-10, thyroid stimulating hormone (TSH), thyroid hormones, including T3 and T4, antithyroglobulin antibodies (ATGAb), thyroid peroxidase antibodies (TPOAb), ESR, RF, ANA, and CRP were determined. Results: A significant reduction in the circulating T3 levels compared to the healthy controls (0.938±0.477 vs 1.345±0.44 nmol/L and p=0.001) with a significant reduction in the circulating total T4 level (47.9±28.41 vs 108±19.49 nmol/L and p=5.546E-06) with a serum TSH level within the normal reference value. IL-6 and IL-10 concentrations rose to a high significant level compared to the controls. By subgroup analysis, we have noticed a high significant reduction in T3 and T4 concentration among the two subgroups of patients and their controls (p=3.294E-05 and =9.816E-05 respectively), they differ significantly as well, in both IL-6 and IL-10 elevations (p=5.864E-34 and = 2.110E-18 respectively). Conclusions: the proportion of patients with subnormal serum T3, total T4 and TSH levels was highest in SLE patients, and they displayed the highest mean IL-6 and IL-10 concentrations (192.5±45.1 ng/L &122.95±46.1 ng/L, respectively) compared with the RA patient subgroup (82.95±28.9 ng/L & 69.05±44.0 ng/L, respectively). (Journal of American Science 2010; 6(9):924-931). (ISSN: 1545-1003).