I-131 scan dose
I had a whole body scan with I-131 to check for recurrent thyroid cancer on 10/21/11. I weaned my 18 month old daughter before the scan. She was only nursing once a day for a short period of time before weaning. She did not want to wean and is indicating that she would still like to nurse. I know that I haven't completely dried up yet. I'm not sure how much the scan dose was, but I asked the nuclear medicine tech and he said that the I-131 should be out of my system in two weeks. Is this the case? I don't want to hurt my daughter, but if she wants to nurse I have no problem allowing her to do so, either.
I-131 has a radioactive half-life of 8 days. After 40 days, 98% is decayed away. It is hard to advise you with so little data, such as what was the dose in millicuries, do you have thyroid gland, etc.
If you have not gland, then 2 weeks is probably OK, as most of the I-131 would be cleared by the kidney and eliminated quickly.
If you have a gland that is still present, OR functioning, then I'd wait at least 30-40 days.
Tom Hale PH.D.