A follow-up study over 3 years in Graves’ disease patients – Predictors of remission

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Decreases of Anti-TSH receptor antibody levels (TRAb) under antithyroid therapy are reported to be predictive for remission of Graves’ hyperthyroidism. Furthermore non-detectable TSH levels in untreated patients who are in clinical remission, are occasionally found, but the clinical significance is not understood yet. 88 Patients with Graves’ Disease were followed over a medium period of 3 years. At 7 timepoints TSH, fT3, fT4 and thyroid antibodies (ultrasensitive TSH- and luminescence receptor TRAb – assay) were measured. At the last timepoint 76% of patients were in remission receiving either levothyroxine (49%) or no therapy (27%), 24% were under ongoing antithyroid therapy. At this time patients in remission not requiring drug therapy previously had received antithyroid medication for a mean time of 12.7 months, patients requiring levothyroxine substitution had previous antithyroid therapy for a mean time of 23.1 months. Patients under ongoing antithyroid therapy at point 7 were treated for a mean of 39.8 months. Mean TSH levels in patients without therapy were 1.158 mU/ml (±0.915), in patients receiving levothyroxine 1.966 mU/ml (±2.689) and in patients on antithyroid drugs 2.314 mU/ml (±4.043). TSH levels in the non-treated group were significantly lower (p<0.05) than in patients on levothyroxine or antithyroid therapy. TRAb were significantly lower in the untreated group (mean 1.64±1.55 U/l) than in the levothyroxin-treated patients (3.22±6.35 U/l, p<0.05) or in the antithyroid therapy group (3.78±3.26 U/l, p<0.05). Unlike reported by others we observed only one female patient with undetectable TSH levels in the clinical and biochemical remission patient subset. This patient had non-detectable TRAb-levels at the last timepoint of follow-up. The decrease of TRAb during treatment and subsequently low TRAb levels seem to be a reliable predictor of the remission of Graves’ hyperthyroidism, in our investigated Graves’ patients in remission we did not observe a substantial subset of patients with non-detectable TSH-levels.