INTERLEUKIN-6 - A MARKER OF THYROID-DESTRUCTIVE PROCESSES

Increased serum interleukin-6 (IL-6) concentrations have recently been reported in patients with subacute thyroiditis and in some patients w ith amiodarone-induced thyrotoxicosis, possibly because of cytokine re lease from damaged thyroid cells. In this study, serum IL-6 levels wer e determined by an enzyme-linked immunosorbent assay method in 18 pati ents given percutaneous intranodular ethanol injection (PIEI) for auto nomously functioning thyroid nodule, 12 patients treated with radioact ive iodine (RAI) for Graves' disease or toxic adenoma, and 23 patients submitted to fine needle aspiration (FNA) for nonfunctioning thyroid nodules. Baseline serum IL-6 levels did not differ in the 3 groups. PI EI was followed by a dramatic increase in median IL-6 values from 42 f mol/L (range, <25 to 84) to 381 fmol/L (range, 61-9870; P < 0.0001); t he peak value was attained as little as 10 min after injection. RAI wa s also followed by a significant (P < 0.0001) increase in IL-6 from 52 fmol/L (range, <25 to 84) to 189 fmol/L (range, 119-1417 fmol/L); the increase after RAI was lower than that after PIEI (P < 0.05), and the peak value was attained later (after 24 h). FNA was also followed by a slight, but significant, increase in the serum IL-6 concentration fr om 21 fmol/L (range, <25 to 103) to 109 fmol/L (range, <25 to 360; P < 0.0001 vs. baseline). The increase in IL-6 was correlated with the si ze of nodule or goiter (P < 0.0001), but not with the amount of inject ed ethanol or the dose of radioiodine delivered to the thyroid. Serum thyroglobulin also increased after PIEI, RAI, or FNA, but no significa nt correlation could be demonstrated with the increase in IL-6. The re sults of this study support the concept that in the absence of nonthyr oidal illnesses, which are often associated with increased serum conce ntrations of the cytokine, IL-6 can be regarded as a useful marker of thyroid-destructive processes.