MICRONUCLEI INDUCTION BY I-131 EXPOSURE - STUDY IN HYPERTHYROIDISM PATIENTS

To evaluate the eventual genetic damage induced by therapeutic exposur e to I-131, We have studied the presence of micronuclei (MN) in binucl eated peripheral blood lymphocytes from a group of 28 hyperthyroidism patients who received I-131 sodium iodide, via oral administration. Th e study was conducted over time and blood samples were obtained before the treatment, and 1 week, 1 month and 3 months after it. The results obtained indicate a positive relationship between dose and BNMN frequ ency as calculated by the linear regression coefficient, showing signi ficant increases in the frequency of MN and BNMN (binucleated cells wi th MN) in the subgroup of patients that received more than 500 MBq. Ta king into account that the patients studied were treated with relative ly low doses of I-131, our positive results support the view that the MN assay is sensitive enough to monitor the chromosome damage resultin g from the exposure.