1987 Volume 34 Issue 6 Pages 821-829
Serum total thyroxine (T4), total triiodothyronine (T3), T4-binding globulin (TBG), free T4 (FT4) and free T3 (FT3) concentrations and the T3-uptake (T3-U) value were estimated in 11 patients with subacute thyroiditis, and compared with the same parameters in 11 patients with Graves' disease, whose serum T4 concentrations were similar to the former group. Seven patients with subacute thyroiditis, who were treated with dicrofenac sodium alone, were investigated as to the sequential changes in serum parameters during their clinical courses.
The mean serum T3-U value and FT4, T3 and FT3 concentrations in patients with subacute thyroiditis were increased, but all were significantly lower than those in patients with Graves' disease (p<0.01, p<0.001, p<0.001 and p<0.001, respectively). Three patients with subacute thyroiditis, who showed shorter duration of symptoms than 10 days, had serum TBG excess. Thus the mean (±SD) serum TBG concentration (26.5±8.4 μg/ml) was significantly higher than that (18.3±2.9 μg/ml) in patients with Graves' disease (p<0.02). The ratios of serum T3 to T4 and FT3 to FT4 in patients with subacute thyroiditis were also significantly lower than those in patients with Graves' disease (p<0.001 and p<0.001, respectively). The serum FT4 in 7 patients treated with dicrofenac sodium alone decreased to the normal range after 3 to 8 weeks from the onset of the illness. In 3 patients with TBG excess and one patient (TBG; 29.0 μg /ml), serum TBG declined in consequence of the serum FT4 normalization. In 20 samples which showed a higher serum FT4 level than 2.0 ng/dl, there was a significant and inverse correlation between serum TBG and the intervals from the onset of illness (r=-0.54, p<0.02).
These results indicate that in some patients with subacute thyroiditis the serum TBG increase induced by as yet unidentified factors may be found in the early phase of this disease, and that higher serum TBG in patients with subacute thyroiditis may contribute partly to the difference between serum T3-U and FT4 in subacute thyroiditis and Graves' disease despite a similar serum T4 concentration.
