The effect of iodine prophylaxis on the frequency of thyroiditis and thyroid tumors in Southwest, Iran.

OBJECTIVE To investigate the effect of the salt iodization program, which was initiated in 1989 on frequencies of thyroiditis and papillary carcinoma in Fars province of Iran, which was previously an iodine deficient area. METHODS Four hundred and eighty-two thyroidectomy specimens belonging to the pre-iodization period from 1983 to 1988, and 466 post iodization specimens from 1998 to 2003 were re-examined for presence of lymphocytic infiltration and types of thyroid tumors. This study was carried out in Shiraz University of Medical Sciences, Iran. RESULTS The frequency of lymphocytic infiltration in non-neoplastic specimens increased from 30-60.5% after salt iodization (p<0.001). Background of lymphocytic infiltration in neoplastic specimens also increased from 18.5-61% after iodine prophylaxis (p<0.001). The frequency of papillary carcinoma in neoplastic specimens increased from 15-43% (p=0.01) and that of follicular adenoma decreased from 69-32.5% (p<0.0001). CONCLUSION Salt iodization is associated with an increased occurrence of histologic thyroiditis and papillary carcinoma.