Increased serum
interleukin-6 (IL-6) concentrations have recently been reported in patients with
subacute thyroiditis, possibly because of
cytokine release from damaged thyroid cells. To investigate the changes in serum
IL-6 concentrations in
subacute thyroiditis during treatment with
corticosteroid, serum
IL-6 concentrations were determined by an
enzyme-linked
immunosorbent assay method in five patients with
subacute thyroiditis. Serum
IL-6 concentrations were increased moderately, and simultaneously, serum levels of T4,
thyroglobulin, and
C-reactive protein and erythrocyte sedimentation rate were increased markedly. The treatment with
prednisolone rapidly and progressively decreased serum levels of
thyroglobulin, T4, and
C-reactive protein and the erythrocyte sedimentation rate. In contrast, serum
IL-6 concentrations increased markedly 7 days after the treatment with
prednisolone in all five patients and two of five patients showed further increases in serum
IL-6 concentration on the 17th day. The rise in serum
IL-6 levels in untreated patients with
subacute thyroiditis in this study is compatible with previous reports. The rise in serum
IL-6 levels
after treatment with
corticosteroid in
subacute thyroiditis may reflect the dissociation between the persistent release of
IL-6 from the damaged thyroid cells, immediate inhibition of secondary inflammatory reactions by
corticosteroid, and the release of
thyroglobulin and T4 from performed
colloid stores in follicular lumen destroyed by
subacute thyroiditis.