A prospective evaluation of early thyroid dysfunction on completion of neck radiotherapy.

The purpose of this study was to examine thyroid dysfunction in the early phase of radiotherapy to the head and neck region. Forty-seven patients receiving neck irradiation including the thyroid gland were included. Twenty-eight patients had undergone either a functional or radical neck dissection and in 19 patients radiotherapy was the primary treatment. Compared to the pre-treatment values, there was a significant fall in the TSH level at completion of radiotherapy in the non-operated patients and a non-significant fall in the operated patients. The TSH was also significantly lower in the non-operated group at the end of treatment compared to the operated group. There was a significant fall in the FT3 and significant higher in the FT4 at the end of radiotherapy for both groups. This study shows that even during completion of radiotherapy to the head and neck region changes in thyroid function were observed for both previously operated and non-operated patients.