PT - JOURNAL ARTICLE AU - Megan Zare AU - David Lewis AU - Michael Richardson TI - Robustness of Male Treatment Failure with I-131 in Hyperthyroidism DP - 2016 May 01 TA - Journal of Nuclear Medicine PG - 1707--1707 VI - 57 IP - supplement 2 4099 - http://jnm.snmjournals.org/content/57/supplement_2/1707.short 4100 - http://jnm.snmjournals.org/content/57/supplement_2/1707.full SO - J Nucl Med2016 May 01; 57 AB - 1707Objectives Radioactive iodine therapy has been used as a first-line treatment for hyperthyroidism as a result of Graves’ disease, Toxic adenoma and multinodular goiter, however efforts to achieve the best treatment dose have never been ideal. Euthyroid outcome as an ultimate goal for treatment is favored, nonetheless hypothyroidism is a widely acceptable outcome. Therapy using a fixed dose versus treatment base upon calculated dose has been debated. Resistant cases following therapy have always been challenging. Therefore, identifying factors leading to variable outcomes are of utmost importance to reduce treatment failure. Prior studies by us and others have suggested the effect of gender on treatment failure.Methods Retrospective review of the medical records from consecutive patients receiving I-131 treatment between 1/1/2007 until 12/31/2012. A total of 210 patients were included in the analysis, with 144 women and 66 men. The mean age was 44 years for females and 42 years for males. The Marinelli-Quimby formula was used for dose calculation to deliver 10,000 cGy. A new dosing algorithm was used to deliver 13mCi or higher for women and 14mCi or higher for men.Results Logistic regression analysis shows a statistically significant effect of gender on treatment outcome following radioiodine therapy. Specifically, men were 1.6 times more likely to have persistent hyperthyroidism requiring retreatment (p = 0.04). No other variables were significantly associated with failure. Other factors such as type of disease, gland weight, and thyroid lab indices did not show statistical significance. There was a drop in failure rate from 16.8% to 8.3% using new dosing scheme, compared to prior study.Conclusions The results of our series indicate that men have a higher likelihood of treatment failure following radioiodine therapy. This suggests that male patients may benefit from higher radioiodine doses. These findings were similar to prior report given by our group published in meeting abstract at JNM 2010 and thus appear extremely robust.