April 2003 -- While radioiodine (RAI) has been used for more than half a century, and is generally considered safe by the conventional medical establishment, there are still a number of aspects of RAI therapy that are considered controversial.

Researchers have established that RAI carries a small (but definite) risk of causing progression of Graves' ophthalmopathy.

Researchers have established that if the antithyroid drugs carbimazole (or methimazole) are stopped 3-5 days before RAI, they do not influence the effectiveness of RAI. Propylthiouracil (PTU), however, appears to take longer to clear out of the system, and makes a patient more resistant to RAI therapy, and should, therefore, be stopped at least two weeks prior to RAI. If the PTU cannot be stopped, a higher dose of RAI may be appropriate.

Taking antithyroid drugs up until the RAI treatment, or taking it within 7 days after the treatment, however, does appear to reduce the effectiveness of RAI.

Researchers have determined that surgery is the first choice in patients with a large goiter. When RAI is used as a goiter treatment for those who can't have surgery, or prefer not to, it can help with tracheal compression and breathing, but only reduces the size of the thyroid approximately 30 to 40%.

Source: Bonnema, et. al., "Controversies in radioiodine therapy: the relation to ophthalmopathy, the possible radioprotective effect of antithyroid drugs and the use in large goitres," European Journal of Endocrinology, Issue 46, 2002.

FOR MORE INFORMATION ABOUT GRAVES'/HYPERTHYROIDISM

• The 10 Things Your Doctor May Not Have Told You About Graves’ Disease
• Diagnosing and Managing Graves' Disease
• Questioning the Rush to RAI: Graves' Disease: A Practical Guide
• Graves'/Hyperthyroidism Links