RESUMO
Background: Radioiodine treatment fails in 17 percent of patients with Basedow Graves disease (BGD). Aim: To assess the frequency and possible associated factors of treatment failure of the first radioiodine dose in patients with BGD. Material and Methods: Review of medical records of patients with BGD treated with radioiodine at a general hospital between 2004 and 2008. Normal thyroid function or hypothyroidism ensuing after treatment were considered as treatment success criteria. Results: According to the databases of the hospital, 298 patients received radioiodine in the study period. Of these, 254 medical records were recovered and 86 were analyzed. Treatment success and failure was recorded in 67 (78 percent) and 19 (22 percent) patients, respectively. The mean dose used was 12 +/- 2 mCi. Clinically determined goiter size and a high free thyroxin level were significantly associated to treatment failure. The area under the receiver operating characteristic curve (ROC) for a thyroid weight over 60 g, estimated clinically was 0.73, rendering a sensitivity and specificity of 63 and 89 percent respectively, for this parameter as predictor or treatment failure. Conclusions: Thyroid gland size may be a predictor of radioiodine treatment failure. However the variability of the clinical estimation of this parameter casts doubts about its usefulness.