ISLET-CELL AND GLUTAMIC-ACID DECARBOXYLASE ANTIBODIES IN HYPERTHYROIDPATIENTS - AT DIAGNOSIS AND FOLLOWING TREATMENT

Objectives. To study the frequency of islet cell (ICA) and glutamic ac id decarboxylase (GAD-Ab) antibodies in patients with hyperthyroidism of different types at diagnosis before treatment and in the euthyroid state following treatment. Setting. Department of Endocrinology, Malmo University Hospital, Malmo, Sweden. Subjects and design. Blood sample s were collected at diagnosis from 129 hyperthyroid patients, and abou t 6 months later, from 78 of the patients (euthyroid state). Ninety-tw o patients had Graves' disease (69 females and 23 males, median age 49 years, range 17-85 years), and 37 patients had toxic nodular goitre/s olitary toxic adenoma (34 females and three males, median age 69 years , range 24-86 years). Interventions. Most patients were treated by rad ioactive iodine following the first blood sample. Main outcome measure s. ICA and GAD-Ab in serum. Results. At diagnosis of Graves' disease, ICA were detected in two out of 92 (2.2%) patients, two out of 85 (2.4 %) without diabetes mellitus and in the euthyroid state in one patient , None of the patients with toxic nodular goitre/solitary toxic adenom a had detectable ICA. At diagnosis of Graves' disease, GAD65-Ab as wel l as GAD67-Ab were detected in 11 out of 85 (13%) patients without dia betes, As many as six out of 11 GAD67-Ab-positive patients were GAD65- Ab negative, In the euthyroid state, GAD65-Ab were found in six out of 51 (12%) and GAD67-Ab in eight out of 51 (16%) of the non-diabetic Gr aves' disease patients. The frequencies of GAD65-Ab and GAD67-Ab in to xic nodular goitre/solitary toxic adenoma, diabetes excluded, were 3 a nd 0%, respectively, in the hyperthyroid state. Conclusion. The freque ncy of ICA in patients with hyperthyroidism is not increased as compar ed to the background population, GAD-Ab seems to be associated with Gr aves' disease and not with hyperthyroidism. The presence of GAD67-Ab i n GAD65-Ab negative sera from patients with Graves' disease indicates autoreactivity against a specific GAD67 epitope.