her life.
Thyroid hormone replacement is not obligatory for those who develop only temporary hypothyroidism, although it is possible that patients in this group should receive replacement hormone, for their glands have been severely damaged and they are likely to develop hypothyroidism at a later date. Perhaps these thyroids, under prolonged TSH stimulation, may tend to develop adenomatous or malignant changes, but this has not been observed.
Many middle-aged women gain weight excessively after radioactive iodide treatment of hyperthyroidism. Usually such patients are on what is presumed to be appropriate T4 replacement therapy. Tigas et al note that such weight gain is less common after ablative therapy for thyroid cancer, in which case larger doses of thyroxine are generally prescribed. Thus they question whether the excessive weight gain after radioactive iodide treatment of Graves’ disease is due to the fact that insufficient thyroid hormone is being provided, even though TSH is within the “normal” range. They suggest that restoration of serum TSH to the reference range by T4 alone may not constitute adequate hormone replacement [ 69a].
Permanent replacement therapy (regardless of the degree of thyroid destruction) for children who receive 131-I has a better theoretical basis. In these cases, it is advisable to prevent TSH stimulation of the thyroid and so mitigate any tendency toward carcinoma formation.
Exacerbation of thyrotoxicosis–
During the period immediately after therapy, there may be a transient elevation of the T4 or T3 level , but usually the T4 level falls progressively toward normal. Among treated hyperthyroid patients with Graves’ disease, only rare exacerbations of the disease are seen. These patients may have cardiac problems such as worsening angina pectoris, congestive heart failure, or disturbances of rhythm such as atrial fibrillation or even ventricular tachycardia. Radiation-induced thyroid storm and even death have unfortunately been reported [71- 73]. These untoward events argue for pretreatment of selected patients who have other serious illness, especially cardiac disease, with antithyroid drugs prior to 131-I therapy.
Other Problems Associate With 131-I Therapy The immediate side effects of 131-I therapy are typically minimal. As noted above, transient exacerbation of thyrotoxicosis can occur, and apparent thyroid storm has been induced within a day (or days) after 131-I therapy. A few patients develop mild pain and tenderness over the thyroid and, rarely, dysphagia. Some patients develop temporary hair loss, but this condition occurs two to three months after therapy rather than at two to three weeks, as occurs after ordinary radiation epilation. Hair loss also occurs after surgical therapy, so that it is a metabolic rather than a radiation effect. If the loss of hair is due to the change in metabolic status, it generally recovers in a few weeks or months. However hair thinning, patchy alopecia, and total alopecia, are all associated with Graves’ Disease, probably as another auto-immune processes. In this situation the prognosis for recovery is less certain, and occasionally some other therapy for the hair loss (such as steroids) is indicated. Permanent hypoparathyroidism has been reported very rarely as a complication of RAI therapy for heart disease and thyrotoxicosis[ 74- 76]. Patients treated for hyperthyroidism with 131-I received approximately 39 microGy/MBq administered (about 0.144rad/mCi) of combined beta and gamma radiation to the testes. This is reported to cause no significant changes in FSH, but testosterone declines transiently for several months, and there is no variation in sperm motility or % abnormal forms (76.1). Long term studies of patients after RAI treatment by Franklyn et al (76a) show a slight increase in mortality which appears to be related to cardiovascular disease, possibly related to periods of hypothyroidism.
Worsening of ophthalmopathy after RAI—
-In contrast to the experience with antithyroid drugs or surgery, antithyroid antibodies including TSAb levels i