fluctuatubg TSH with Hashimoto's

[gilHI]

If this isn't an appropriate question for this forum, would you please direct me to another forum?
I am a 58 year-old woman. Over the past year, on the same T4 dosage (.075) my TSH results have been as follows:
8/09: 1.24
12/09: .34
1/10: 1.32
8/10: .27
My free T4 stayed the same over the same year (1.2-1.3) and my T3 has not changed in the past 8 months (97; it wasn't tested last year).
My internist is suggesting I reduce the dose.  Because I have been feeling poorly (extreme fatigue, weight gain despite intake of 1000 calories per day, memory issues etc) I have asked for parathyroid, iodine, Vit. D tests. Vit. D was on the low side so I'm taking supplements, but other tests were normal. I do have fibromyalgia. I also could have symptoms of high thyroid levels, as I have hot flashes and heart palpitations.
My questions are (1) why would TSH fluctuate so much, (2) what could explain it, and (3) should I have any other tests?
Thank you very much.

[gilHI]

Thank you very much for your comments.

[Mark Lupo, M.D.]

Fluctuations like this are not uncommon - sometimes due to generic meds, inconsistency with meds, timing of dose in relation to blood draw (should not make sig difference with T4), absorption of T4 meds, interference with supplements/other meds......etc....

Would consider retest and if still lowish TSH, then decrease dose (to 6 1/2 tablets per week for example).