What are the ranges on your FT4 and TT3? Ranges vary lab to lab, so you have to post them with results.
I does sound like you might have a conversion problem since you felt well immediately on the Armour.
I've always taken T4-only meds. I had been on 75 mcg Levoxyl, then my endo raised that to 81.5 mcg, which is when I went hyper. At that point, I went back to 75 mcg and was on that for several years. Just this past year, my labs started to tank...FT4 at bottom or just below range. The first time my FT4 was that low, my FT3 was still good, but six months later it was considerably below range. I never had a single hypo symptom. However, I was getting concerned that we were seeing a trend, so I increased to 88 mcg Levoxyl.
Unlike most forum members who seem to have to have their FT3 and FT4 levels well up into the range, I'm quite comfortable at the low end.
Slow conversion is different from peripheral thyroid hormone resistance (THR). People with THR have to have serum FT3 concentrations extremely high (sometimes many times the top end of the range) before their cells can take it in. It sounds like you just convert slowly (a fairly common problem), but don't have THR (very rare).
Thanks for your reply, Goolarra. In answer to your request, my FT4 is 0.8, and Total T3 88. My doctor didn't draw a FT3. My endo did talk about pituitary resistance, but thought we didn't need to pursue since I'm doing well on Armour Thyroid. I'm glad that I don't need to worry much about my TSH; I kindof came to that realization when I feel so well now at a level of 7.
With the symptoms I had, I tend to believe there must be a conversion problem peripherally, because the minute I got even the tiniest dose of T3 (in that first dose of 15 mg of Armour Thyroid), I felt immensely better. Does that sound about right? (I had been on Synthroid doses ranging from 50-150mcg, and got nothing but more hyper symptomatic when taking it.)
What med works for you? When you had the hyper symptoms before the PRTH was dx'd, what were you taking? After it was diagnosed, what are you taking for it?
I have an issue with similar symptoms. Although my FT3 and FT4 are both in range, and I have no hypo symptoms, my TSH permanently hovers around 20.0.
My endo has diagnosed pituitary resistance to thyroid hormone (PRTH). My pituitary lacks the enzyme (5'-deiodinase) that converts T4 to T3. This only affects my pituitary; my peripheral conversion is fine. Because my pituitary is starved for T3, it thinks the rest of my body is, too, so it secretes copious amounts of TSH.
The upshot is that my TSH has to be ignored. I have to use FT3 and FT4 as a guide, rather than TSH. TSH is so unreliable in so many cases that everyone should be cautious of TSH.
Before the PRTH was diagnosed, I had hyper symptoms with TSH still around 20.0. That was several years ago, and my TSH continues to misbehave. Sometimes my FT3 and FT4 go up, and so does my TSH. Sometimes they all go down together. And, on rare occasions, they actually do what they're supposed to do.
Do you have current FT3 and FT4 to post? If so, please do with reference ranges (they vary lab to lab and have to come from your own report). I can give you an idea of what I see there, but your symptoms are your best guide.