I had terrible PN in my feet when I was hypo...back before my son was born. I also had carpal tunnel --lost 80% function in both hands while I was pregnant.

I didn't get a firm diagnosis of hypo until I had a radioactive uptake test done...which showed a dead left lobe and goiter in the right side. My tests were not severely off either. The isotope was called technicium.

When I started levothyroxine, it was very slowly. 25mg a day for 3 mons and then 50mcg. I stayed at 50 for a while, then we had very severe winter and lost power for 4 days, I had a hypo crisis, which was terrible. Then I was raised to 75mcg, and that seemed to stabilize me and that is where I stay.

Some people with Hashimoto's can fluctuate up and down.
Also people low in iodine intake can not respond properly.
Using a standard kelp product which mostly have 150mcg..each and take 2 a day...may help.

Then there is peripheral conversion issues. People low in zinc and selenium cannot convert T4 to active T3. So if you take levothyroxine, it may not work...since it is inactive, and needs conversion in the tissues.

It can get very complex. Then there is "reverse T3" which is also inactive.

One of the best resources on the net is Mary Shomon:
http://thyroid.about.com/bio/Mary-Shomon-350.htm

There is considerable disagreement among medical doctors on how to deal with thyroid problems. So it is not easy getting this fixed.

Keep in mind you MUST take the same brand of hormone when testing. Things vary even among brand names! Also always take first thing in the morning, on an empty stomach and no food for an hour. Very critical for absorption...just like the B12 and some other drugs that are given in microgram amounts.