Ok here is the story, as I have Graves, and not up on all the info of Hashi's, I have a family member that is 13 and she was taking meds for Hypothyroid. Her mother took her to a new doctor, which tested her thyroid(god knows what tests they ran, probably just the TSH)and it came back as normal. She had been on meds for Hypothyroid for sometime unsure as to how long but think it was about six months. Now this young lady has gained weight, and the new doctor even said that she was diabetic(type 2). She has been taken off of all thyroid meds, and the mother has even had her taken off of the diabetic meds due to tests that showed she was having very sever low blood sugars. Anyway this doctor told her she wasn't hypothyroid. With Hashi's can you test hypo and then normal and if so how often does this tend to be the case? Her mother is trying to have her tested for some kind of crazy off the wall thing, that isn't approved on children yet. I can't understand why she isn't looking further into the thyroid issue, as it seems to be the most practical and she has already had abnormal labs for thyroid, this child is suffering from depression, and the new doctor wanted to have her checked for being bipolar. I am worried this child may be being put threw the ringer for nothing other than what she was on meds for in the first place. They never did do any antibody testing, and if they did never mentioned what the results were to her mother. With Hashi's do they just need to do antibody testing to find out if she has it, or are there other tests they should do?
Boy, we had a similar mess with one of our kids. Very low energy teen, low body temps (96 degrees-ish); pediatrician thought depressed, and the current clinical thinking is that depression in kids & teens means bipolar.
Because neither psychiatrists (several wishywashy evals, differing dxs, no bipolar) nor peds would test thyroid (despite extensive family history), we ended up doing it ourselves through HealthCheck USA. We had all the antibodies run, plus the frees (free T3 & free T4), plus TSH. It was a package deal, but not on their standard menu, if I recall correctly.
It turned out our son DID have a bargain-basement free T4 level. I do blame myself -- I had cooked low sodium for years, & I believe my son had an iodine deficiency. Once we started adding iodine back into his diet(not excessively), there was major energy improvement.
I'm not saying that iodine insufficiency is your young relative's problem, but her family could follow a similar route with the testing at HCUSA if they wanted to. Even if testing had proven perfectly normal, for us, it was worth it to spend the $150 or so. We just slept better knowing one more important base was covered.
If you are a reasonably close blood relative (aunt or grandma), your own thyroid problem is part of familial medical history.
Your question about the bobbing around of test results is a good one. IME, the TSH bobs around more than the frees. For a Hashi's dx, typically you need antibodies, or biopsy findings. 'Course, you don't find those unless the specific tests are done. It's good to test for all the antibodies. If she does indeed have any type of thyroid antibodies, that is a situation that calls for attention.