Thyroid function after radiotherapy and laryngectomy for carcinoma of the larynx.

Total levels of thyroxine (T4) and thyroid-stimulating hormone (TSH) were measured in 37 patients who had previously had carcinoma of the larynx treated by radiotherapy and total laryngectomy with thyroid lobectomy. Ten percent of the patients had clinical features of hypothyroidism and 30% had total T4 levels below the lower limit of normal. A further 40% had results in the low normal range. Forty-four percent of patients had raised TSH levels, 90% of these having low or low normal T4 levels. The histology of the thyroid gland was normal in all 37 patients. Attention should be given to preserving intact the vasculature of the contralateral thyroid lobe whenever it is necessary to remove the ipsilateral thyroid lobe during a laryngectomy. Proper postoperative assessment of thyroid gland function is desirable in all these patients to identify those at risk of hypothyroidism and to avoid unnecessary morbidity.