The role of age in the development of hypothyroidism after treatment with radoiodine.

The authors have studied the role of age in the development of posttherapeutic hypothyroidism in 141 patients treated with radioiodine for thyrotoxicosis. The minimum time of the follow up after treatment was 10 years. The patients were divided into two groups according to age at which the treatment was administered. The critical age was 55. The incidence of posttherapeutic hypothyroidism was significantly greater in the elderly patients. There was a gradual increase of incidence of posttherapeutic hypothyroidism during the 10 year follow up. The dangers of the thyroid treatment in the elderly hypothyroid patients with persisting cardiac involvement may be reduced by a concomitant administration of beta blocking agents.