Hypothyroid (under control w/ synthroid) but did tpoab & it's not autoimmune. dr says probably genetic. should i ask to test other causes to be sure?

Hypothyroid: If you are feeling well and Dr thinks you are doing OK I would think not.

Ask an expert: You need to see an endocrinologist for assessment, s/he would know better and direct your care appropriately, if you have already seen one, then keep the follow up or ask for a second opinion by a thyroidilogist, thyroid gland tests are complex and at times need an expert to decipher them, good luck