very low TSH

[whitetiger]

41 yr old female (5'9")in good health.  DX 1990 with Hashimoto's Thyroiditis.  All symptoms classic of Hashimoto's except a 30lb weight loss in 6 months without dieting. Beginning weight 147lbs down to 117lbs. Maintained 10 yrs on 0.175mg Synthroid and weight leveled out to 132lbs +/- a few pounds.  Developed hand tremors, heart palapations, irritability so dose lowered to 0.150mg and maintained for approx 6 yrs.  Again developed severe hand tremors, heart palapations, drastic weight loss, insomnia, etc.  TSH level 0.01, T4 25, T3 4.7 so Sythroid has been adjusted to 0.125mg.  

My Endo. retired just before my first problem tolerating the med 6 yrs ago and my GP is hesitant to refer to another Endo.
What causes the body to suddenly not tolerate the medication as well as before?  Nothing in my life has changed whatsoever except the normal aging process.  I do not take any other medications and am otherwise healthy and fit.  Should I push to see a specialist or check for underlying causes.

[Mark Lupo, M.D.]

Change to generic, change in timing of dose (ie in relation to meals, supplements, etc), medication interractions (not the case here).....sometimes it is hard to know.  

I would decrease the dose as you are doing -- if you continue with a low TSH despite loering the dose, then you may need to stop the med to make sure that your thyroid is not capable of producing hormone again (VERY rare).  Goal TSH is around 1.

As a specialist, I would say see a specialist, but your GP is on the right track in terms of lowering dose and rechecking in 6-8 weeks.

[whitetiger]

Thank you for your response.  I think I will push to see a specialist since none of the factors you listed are apparent in this case (i.e brand of med (no substitutions written on script), supplements, time of dose, meals etc).

[lhowell]

I've read numerous times that patients with Hashimoto's have a tendency to toggle from hypo to hyper.  That could be the case.