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Subclinical hypothyroidism is quite common. In the Whickham survey
in northeast England, Tunbridge and his co-workers found in adults a prevalence of
hypothyroidism of 7.5% in women and 2.8% in men (3). The prevalence increased with age. In
the Framingham study 10.3% of the population (5.0% of men, 13.6% of women) had a high
serum TSH only (4). Wang and Crapo surveyed the literature in 19975. They quote prevalence
rates of subclinical hypothyroidism ranging from 1.3 to 10.3% in persons of both sexes,
0.7 to 5.7 in males and 3.0 to 13.6% in females.
Persons with a high TSH had more frequently positive antithyroid autoantibodies (AAB), than those with a normal TSH. An increased prevalence is found in patients with other autoimmune diseases, especially type I diabetes6. In the USA 2% of pregnant women had subclinical hypothyroidism and of these 58% had also positive thyroid autoantibodies (7). In summary, about 5% of adult elderly persons have subclinical hypothyroidism. The prevalence increases with age, is higher in females than in males, and in persons with positive AAB. |
