RELATIONSHIP BETWEEN CIGARETTE-SMOKING AND HYPOTHYROIDISM IN PATIENTSWITH HASHIMOTOS-THYROIDITIS

This retrospective study examined the relationship between smoking his tory and thyroid function in 387 women patients with Hashimoto's thyro iditis (mean age+/-SD=50.5+/-12.7 yr). The same analysis was done in 2 38 randomly chosen women patients with nodular goiters (mean age=45.3/-14 yr) and 166 control women (mean age=47.7+/-14.2 yr). In patients with Hashimoto's thyroiditis, there were 256 non smokers, 110 smokers, and 21 smokers. Among the 110 smoking patients with Hashimoto's thyro iditis, 76.4% were hypothyroid, whereas the prevalence of hypothyroidi sm was 34.8% among the 256 non smokers. Among the 21 ex-smokers with H ashimoto's thyroiditis, the majority of patients (61.9%) were hypothyr oid, suggesting that cessation of smoking does not appear to reverse h ypothyroidism. The percentages of smokers in the hypothyroid group, th e subclinical hypothyroid group, and the euthyroid group were 45.2%, 1 8%, and 11.3%, repectively, in patients with Hashimoto's thyroiditis. The greatest serum levels of thiocyanate (an antithyroid substance gen erated by smoking) were found in those who both smoked and had hypothy roidism. Thus, an increase in serum thiocyanate concentration from smo king may contribute to the development of hypothyroidism in patients w ith Hashimoto's thyroiditis. Smoking related hypothyroidism was not se en in patients with nodular goiters. Our results suggest that smoking may increase the risk of hypothyroidism in patients with Hashimoto's t hyroiditis. (C) 1996, Editrice Kurtis