SERUM LEVELS OF INTERLEUKIN-6 AND TUMOR-NECROSIS-FACTOR-ALPHA IN HYPERTHYROID PATIENTS BEFORE AND AFTER PROPYLTHIOURACIL TREATMENT

Contrary to the usual inhibitory role of tumor necrosis factor-alpha ( TNF-alpha) in thyroid metabolism, it also has specific stimulatory eff ects in autoimmune thyroid disorders, including induction of HLA class II antigen-presenting cell-T cell interaction, Despite high intrathyr oidal concentrations, various studies were not able to demonstrate hig h serum levels of TNF-alpha in patients with Graves' disease. To inves tigate this discrepancy we determined TNF-alpha and interleukin 6 (IL- 6) levels in 25 hyperthyroid patients who responded to propylthiouraci l treatment (16 with Graves' disease and nine with toxic multinodular goiter) and compared them with the levels found in euthyroid patients with simple diffuse goiter (n = 15) and normal healthy controls (n = 1 5). Median IL-6 levels were high in both Graves' disease and toxic mul tinodular goiter patients before propylthiouracil treatment (23 and 26 .5 pg/ml, respectively). After restoring euthyroidism there was a stat istically significant decline to near-normal levels (3 and 10 pg/ml, r espectively). On the other hand, median serum TNF-alpha levels were hi gh only in Graves' disease patients (20 pg/ml) and could not be normal ized with antithyroid medication (20 pg/ml) compared to that of contro ls (5 pg/ml). Tumor necrosis factor-alpha, but not IL-6, was found to be high in the sera of Graves' disease patients when euthyroid, which may be due to an ongoing antigen-antibody interaction, a feature of au toimmune attack. It remains to be determined whether the degree of TNF -alpha and/or IL-6 elevation will be a predictor of disease recurrence .