Thyroid function tests of elderly in a geriatric center in Rasht

Prevalence of thyroid diseases increases with age. 4% to 17% hypothyroidism and 2% thyrotoxicosis has been reported in elderly population over 60 years of age. The age and sex distribution of all thyroid antibodies in men has shown no significant variation with aging, but a marked increase with age was shown in women. Some studies have suggested that thyroid autoimmunity is exacerbated in iodine sufficient areas. To evaluate geriatric thyroid function in iodine deficient area we conducted this study in Rasht, which is a known iodine deficient district in North Iran. The study included physical exam for goiter and thyroid function tests on 128 healthy elderly residents of an old people’s home in Rasht. Mean age of 42 males was 72.5±7.5 years and 86 females 73.9±10.6 years. 23 cases (18%) including 4 men (8%) and 19 women (21%) had clinical goiter. 8 cases (6.25%) had TSH>5 mU/L. Tsh was > 10mU/L in 2 of them (1.5%). Only 2 cases had T4<4.5 μg/dL, who suffered from secondary hypothyroidism. Anthithyroid antibodies were negative in all the subjects. There was no significant age related change in T4, FTI, and TSH among different age decades. In either sex, T3 was significantly decreased in older subjects. In this study, incidence of hypothyroidism was 6.25% equally in both genders, and all these patients had subclinical hypothyroidism, surprisingly, with negative thyroid autoantibodies. These findings are in contrast with the high incidence of hypothyroidism and antithyroid antibodies shown in other studies. This difference might be due to iodine deficiency in this area.