Radiation-Related Thyroid Dysfunction: Implications for the Treatment of Hodgkin's Disease

Abstract

Thyroid-stimulating hormone (TSH) and thyroxine (T4) were measured in sera from 214 patients with Hodgkin's disease. The literature was reviewed for patients with lymphoma or head and neck carcinoma who had received prior radiation therapy that encompassed the thyroid. Among 169 patients who had been treated with mantle radiation therapy at our center, 112 (66%) had evidence of thyroid dysfunction, including 43 with depressed T4 levels. Among 45 who did not receive mantle irradiation, only three had evidence of dysfunction and none of these had T4 depression. Thyroid dysfunction developed slowly, with less than 15% of patients tested during the first year showing dysfunction and the maximum of 66% reached at about 6 years. This entity is very common in lymphoma patients yet often is overlooked except in instances of specific thyroid function evaluation for research. A substantial proportion of patients with head and neck carcinoma develop thyroid dysfunction after irradiation, especially if therapy includes hemithyroidectomy. Serum TSH measurement every 6 months for at least 5 to 6 years after irradiation will detect early thyroid dysfunction. All patients with elevated serum TSH should be treated with sodium levothyroxine, regardless of whether they are clinically hypothyroid.