TSH is a pituitary hormone that is supposed to accurately reflect levels of the biologically active thyroid hormones, Free T3 and Free T4. In reality TSH cannot be shown to correlate well with either, much less correlate well with symptoms, which should be the first concern.
The main value for TSH is in the initial diagnosis. After starting on thyroid med it is basically useless as a test. Scientific studies have shown that Free T3 correlates best with hypo symptoms while Free T4 and TSH do not correlate at all. In addition, when taking thyroid med, patients frequently find that in order to raise their Free T3 and Free T4 enough to relieve symptoms, their TSH becomes suppressed below range..
A good thyroid doctor will treat a hypo patient clinically by testing and adjusting Free T3 and Free T4 as necessary to relieve symptoms, without being constrained by resultant TSH levels. You can get some good insight into clinical treatment from this letter written by a good thyroid doctor for patients that he sometimes consults with after initial tests and evaluation. The letter is then sent to the participating doctor of the patient to help guide treatment. In the letter, please note the statement, "the ultimate
criterion for dose adjustment must always be the clinical response of the patient."
Another thing to be aware of is that hypo patients often find that their body does not adequately convert the T4 med to T3, resulting in too low Free T3, and hypo symptoms. Your doctor recognized the need to raise your Free T3. I would like to know the ranges for both your Free T3 and free T4, as shown on the lab report. I expect that your Free T4 is adequate, so, instead of raising your T4 med, plus adding Armour, I think it would be better to add some T3 med to your daily dosage. Then the best approach is to continue to slowly increase the T3 med as required to relieve symptoms.
One thing further is that hypo patients frequently are also too low in the ranges for Vitamin D, B12 and ferritin. If not tested for those, I really recommend doing that. Each is very important for hypo patients.
Thank you guys both for those explanations! I didn't realize the reference ranges vary so these are it:
TSH - 0.43 (0.34 - 4.50)
FT3 - 2.60 (2.50 - 3.90)
FT4 - 1.25 (0.54 - 1.24)
I understand now that sometimes the T4 does not convert to the active T3 in your body, hence why T3 would be low. But how come T4 is high? Does it just keep producing and producing, and not realize that it's not being converted? I'm assuming the doctor wanted to increase Synthroid based on clinical findings of me having brain fog/fatigue/lack of concentration, and not based on labs alone..but it's odd to want to increase T4 even more.
Am I correct in thinking now that T3 is the hormone that is most responsible for symptoms and thyroid function? And that T4 is just the inactive state that converts it to an active hormone?
PS - Gimel thank you for the Vit D/B12 information, I have a history of that and will get that checked!
Don't forget ferritin also. Very important for good thyroid function. Women need ferritin in the area of 70-80.
Well, your doctor was right; your FT4 is a little high. That's a very low FT4 range. I don't think I've ever seen one that topped out that low before.
Synthroid's active ingredient is T4. So, the 75 mcg you've been taking everyday (along with whatever your thyroid might still be able to produce) is what's making your FT4 level high. No feedback mechanism has been identified for conversion, so we don't really know how the body determines how much to convert.
It is odd to want to increase T4 even more when it's already over range. Typically, increases are on the order of 12.5-25 mcg at a time. So, I would seriously question a 50 mcg increase at this point. I appreciate the fact that he's treating your symptoms, but I find his approach a bit too aggressive. Did you say he was adding Armour as well?
Yes, T4 is the "storage" form of the thyroid hormones. It's made in the thyroid and basically floats around in your bloodstream until it's needed. However, cells can't use T4 until it's converted to T3. Some T3 is made in the thyroid, but the vast majority is converted at the site that needs it.
Thank you! You guys helped me understand this a lot better!! I did research about Armour as well and decided this next month I get a refill I will stop Synthroid altogether and start Armour so I get more T3. Thanks again!