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Old 01-16-2013, 09:41 PM   #4
midwest1
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Re: Question about thyroid levels

Healthy people have TSH around 1 to 1.5 and free T4/3 levels at 50-70% of their ranges. In the textbook world, TSH is supposed to rise once T4/3 become deficient, but in reality it hardly ever works that way. Most of the time, hypoT is caused by auto-antibodies that suppress thyroid hormone production. These antibodies are known to also prevent the rise of TSH, but doctors aren't taught that. It means most people suffer for years in the hypothyroid state before their TSH rises high enough to be diagnosed. Do you have any family history of thyroid or autoimmune diseases? If so, testing for TPO and Tg antibodies is warranted.

Other times, pituitary or hypothalamic dysfunction keeps TSH low while thyroid hormone levels inappropriately fall. Eating disorders can cause TSH to remain low while T4/3 fall.

There are three reasons that come immediately to mind that cause low TSH w. low T4/3.

I won't lie. You may have a hard time finding an MD who'll see your T4/3 too low. Most will dismiss the possibility as long as your TSH looks so "normal". That doesn't mean it isn't worth searching for one, though. Smarter ones are out there, if you look hard enough.

Good luck.
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