INCIDENCE AND PREVALENCE OF THYROID-DISEASE IN ELDERLY WOMEN - RESULTS FROM THE LONGITUDINAL POPULATION STUDY OF ELDERLY PEOPLE IN GOTHENBURG, SWEDEN

The incidence and prevalence of thyroid dysfunction were estimated in a longitudinal study of a representative sample of elderly women at ages 70, 75, 79 and 81. Thyroid-stimulating-hormone concentrations were measured in frozen samples obtained at the ages of 70 and 75 that had been stored for ten and five years, respectively. At the ages of 79 and 81 the serum concentrations of thyroid-stimulating hormone were determined in connection with the sampling. For comparison, thyroid-stimulating-hormone concentrations were also measured in another representative population sample of women at ages 70 (n = 297) and 76 (n = 342), in whom measurements were carried out in direct connection to the clinical study. History of previous thyroid disease, e.g. thyroid surgery and thyroid hormone treatment, was obtained through a questionnaire. Information about previous treatment with radio-iodine was obtained from records. At the age of 70, 1.9% had had thyroid surgery but none had been treated with radio-iodine. L-Thyroxine had been prescribed for 3.5%, and another 3.9% had high thyroid-stimulating-hormone concentrations (> 10.0 mU/l) indicating thyroid hypofunction. Between 70 and 79 years of age, eight of the 514 women had developed high concentrations of thyroid-stimulating hormone and another two women had received treatment with L-thyroxine. Three women had received radio-iodine therapy. In addition, one woman at the age of 81 was discovered to have hyperthyroidism. The retrospective analysis showed that markedly elevated TSH concentrations had been present in several women for at least nine years. The results show that the prevalence of thyroid disease is high in elderly women. The incidence of hypothroidism was estimated to be approximately 0.2%/year and of hyperthyroidism 0.1%/year between the ages 70 and 79. There was no consistent change in thyroid-stimulating-hormone concentrations with age in women without thyroid dysfunction.