Radioactive Iodine Treatment of Graves' Disease: Predictors of Time Interval Greater than 90 Days for Treatment...

Radioactive iodine (RAI) is often used for treating Graves' disease. We study predictors for a time interval greater than 90 days between RAI treatment and success.

This was a retrospective study of 106 patients with Graves' disease seen at a public hospital in suburban New York City. Predictor variables were from demographics, prior treatment history, iodine 131 RAI treatment, and thyroid function prior to RAI treatment.

There were 62.3% that had a time interval greater than 90 days between RAI treatment and success. Only the thyroid function prior to RAI treatment variable of free thyroxine (FT4) had statistically significantly increased odds for time interval greater than 90 days between RAI treatment and success (OR:1.28, 95% CI:1.02, 1.61, p = 0.03). Demographics, prior treatment history, and iodine 131 RAI treatment variables were not significantly associated with time interval greater than 90 days between RAI treatment and success.

Thyroid function measured by FT4 was significantly associated with time interval greater than 90 days between RAI treatment and success. We suggest that the thyroid function variable of FT4 levels at initial diagnosis is most helpful for understanding the prognosis and success rate for using RAI treatment in patients with Graves' disease.