The vast majority of hypo in the developed world is caused by Hashimoto's thyroiditis, which is an autoimmune disease. You might also want to ask the doctor to test for the two antibody markers for Hashi's, TPOab (thyroid peroxidase antibodies) and TGab (thyroglobulin antibodies).
Unfortunately, we do have to be our own advocates these days. Hope your appointment goes well.
Thank you so much for commenting! It seems like I have to direct the doctors to get anything done sometimes, and often they never use or discuss the labs, even when they're abnormal.
The more information I have for the next appointment, the more we will get done. She also has bipolar, anxiety, and learning disabilities, so she may have symptoms of thyroid problems that are confused with other things.
TT4 (total T4, thyroxine) is considered an obsolete test of little value.
FT4, while in range, is very low in the range. Her FT4 is 19% of range, and most of us have hypo symptoms until FT4 is about 50% of range.
FT3 was not tested, and that's the test that correlates best with symptoms.
TSH is also on the low side, and as a rule, when FT4 is low, TSH should be high. So, there's a contradiction there, i.e. TSH is saying she's on the hyper side, but FT4 is saying hypo. FT3 might resolve that contradiction.
Vitamin D is dismal. It's below range, and it should be well up into the range, not just on the bottom. Her doctor should suggest a supplement, and 50,000 IU per week isn't unusual with this kind of deficiency. Don't supplement that much, however, except on your doctor's advice.
T3U is also considered an obsolete test, and despite it's name is actually an indirect measure of T4. T3U can be high when proteins that bind T4 are elevated. It's possible that her other health issues are causing these proteins to be out of whack.
I think these results are off enough that you should pursue it. Ask your doctor to repeat FT4 and TSH and include FT3 this time.
Hope this helps, and best of luck.