Endocrine Abstracts

Aim: The aim of the study was the evaluation of the TSHRAb level changes and the comparison with thyroid function in patients with Graves’ disease treated with ¹³¹I 10 years ago.

Material and methods: The study has been conducted in 67 patients (57 women, 10 men) aged 27–72 y (mean 48 years) with Graves’ disease.

All patients were treated with ¹³¹I due to hyperthyroidism confirmed by fT3, fT4 and TSH examination before treatment. Before therapy and after 10 years of follow-up, TSHRAb levels were measured according to radioreceptor method (‘TRAK Assay’, BRAHMS Diagnostika GmbH). Ten years after ¹³¹I therapy TSH levels with IRMA method have been estimated.

Results: The levels of TSHRAb ranged from 1.3–405 U/l (mean 62.66±107.37 U/l) before therapy. In 18 patients (26.9%) the levels were negative, in 5 subjects (7.5%) uncertain, in 44 patients (65.6%) positive. Ten years after ¹³¹I therapy, the determined TSH levels ranged between 0.04 and 41.82 mIU/l (mean 5.44±7.7 mIU/l) – 49 subjects with hypothyroidism, 17 euthyroidism, 1 hyperthyroidism. The levels of TSHRAb ranged between 2.2 and 48.4 U/l (mean 7.66±7.74 U/l). In 59 patients (88.1%) the levels were negative, 1 person (1.5%) uncertain (this person was diagnosed as hyperthyreosis), 7 persons (10.4%) positive (6 – hypothyreosis, 1 – euthyreosis). In 2 patients (3%) the increase of the TSHRAb levels has been recorded, in 16 persons (23.9%) the antibody levels did not change, however in 49 patients (73.1%) were decreased.

Conclusions: The obtained results have pointed out the prominent (nine times) and statistically significant (P< 0.0001), reduction of TSHRAb levels in a long-term (10 years) follow-up. A long-term ¹³¹I therapy induces hypothyroidism requiring permanent systematic substitutive therapy.