Effects of thyroid status on thyroid autoimmunity expression in surgically induced hypothyroid patients with Graves'...

We investigated, in 20 patients with Graves' disease and presenting with both a surgically induced hypothyroid state and increased serum antibodies (Ab) to the TSH receptor (R) levels, the relationships between thyroid status and the serum TSH-R or peroxidase (TPO) Ab levels under L-T4 treatment and after L-T4 cessation. The prevalence of positive TSH-R Ab (100%) and the log mean TSH-R Ab level (1.41 +/- 0.04%) observed during the surgically induced hypothyroid state decreased (p < 0.001, p < 0.01, respectively) under L-T4 therapy (prevalence of positive TSH-R Ab = 50%, log mean TSH-R Ab level 1.21 +/- 0.05%) and increased again (p < 0.001) after L-T4 cessation (prevalence of positive TSH-R Ab = 85%, log mean TSH-R Ab level = 1.45 +/- 0.06%) to reach levels lower (< 0.01) than that observed during the hypothyroid state for prevalence of positive TSH-R Ab but similar to that obtained during such a state for log mean TSH-R Ab value. The log mean TPO Ab level obtained during the surgically induced hypothyroid state (3.2 +/- 0.5 titer) decreased (p < 0.02) under L-T4 therapy (1.8 +/- 0.2 titer) and increased again (p < 0.02) after L-T4 cessation (3.0 +/- 0.5 titer) to reach a similar level to that obtained during the surgically induced hypothyroid state. There were positive correlations between log TSH levels and log TSH-R Ab values (r = 0.40, p < 0.001) or log TPO Ab levels (r = 0.33, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)