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Radioiodine therapy for hyperthyroidism is associated with a slight increase in long-term mortality
The background of the study. Mortality may be
increased in patients treated for hyperthyroidism, but whether the
increase is due to persistent hyperthyroidism or hypothyroidism
is uncertain. In this study, the long-term mortality of patients
with hyperthyroidism who were treated with radioiodine (I-131) was
determined.
How the study was done. The study subjects were 2668 patients aged 40 years or older with hyperthyroidism treated with I-131. Serum free thyroxine (T4) and thyrotropin (TSH) were measured annually starting after the patients had become euthyroid. Patients who had overt hypothyroidism during follow-up were treated with T4. The status of these patients was determined by a search of the national mortality data base in the United Kingdom. Death certificates were reviewed, and the results were compared with those of all patients of the same age and sex who died in the same year.
The results of the study. There were 2163 women and 505 men (median age when serum TSH was first measured, 62 years). At death or study end, 1212 patients (45 percent) were taking T4.
There were 554 deaths during a median follow-up period of 5.6 years, whereas 487 were expected (standardized mortality ratio, 1.14). There were increases in deaths from cardiovascular diseases in women; respiratory diseases in men; and endocrine and metabolic diseases in women and men combined. All-cause and cardiovascular-disease mortality rates were higher in patients who were never treated with T4 or before T4 was given, but not in those treated with T4. In patients not treated with T4, the all-cause mortality rates were increased in those with low and normal serum TSH values, but not in those with high serum TSH values.
The conclusions of the study. In patients with hyperthyroidism who are treated with I-131, mortality from all causes and cardiovascular disease is increased, but not if they are treated with T4.
The original article. Franklyn JA, Sheppard MC,
Maisonneuve P. Thyroid function and mortality in patients treated
for hyperthyroidism. JAMA 2005;294:71-80.
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| Thyroid Digest Index | | | November 2005 Thyroid Digest |
