Hi Cindy,
From what I understand, a negative test for antibodies doesn’t necessarily mean that your daughter doesn’t have Graves’. I know it sounds weird, but the antibody levels rise & fall for no well-understood reason, so it isn’t always conclusive. For just that reason, many doctors do not rely on the antibody test.
There is such a thing as thyroiditis, which is an inflammation of the thyroid and usually self-corrects within six weeks. I don’t believe it would have produced the scan results you speak of, but I’ve never known anyone for whom that was the problem.
Your best source for information at this point will be your daughter’s doctors. What have they told you so far?
~Ski
NGDF Assistant Online Facilitator