Hi Sarah, just wanted to give you a little info.....

The RAI uptake test is generally done if they are planning on treating you with RAI. The uptake test involves ingesting a tiny amount of RAI to see where it is distributed within the thyroid and in the case of Thyroid ca, the rest of the body too. Although it is a tiny amount for this test, it is generally not recommended to BF mothers, as your endocrinologist suggested.

To look at the general physiology of the thyroid, the most common radioactive agent used is technetium, it behaves like iodine in the thyroid, but unlike iodine it has a short half and does not emit any beta rays. Beta rays are what iodine emits to destroy tissue. So, it is excreted rapidly from the body without causing any tissue damage. For this test it is generally recommended that you either express prior to the test and use that for the next 24 hrs, or use formula.

From the sounds of it, your friend had radioactive iodine for treatment. Treatment follows the uptake test if indicated. The dose of iodine used for treatment in much higher and that is when all the special precautions come in. Separate cutlery, separate beds, limiting close contact with children and pregnant women, etc.

I hope i am making it clearer for you and not more confusing! Please pm me if i can answer any questions about the RAI at all.