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normal free T4 but high TSH
Could anyone help me understand what a normal free T4 and yet a high TSH means ? My TSH came as 20 (twenty) yet my free T4 is within the normal range at 1.11
I don't know what your basic level of knoledge is about thyroid in general, so please forgive me if I tell you things you already know in explaining PRTH.
T3 is the "active" form of the thyroid hormones. T4 is the "storage" form. Your body cannot use T4 until it is converted to T3. Normally functioning thyroids produce both T3 and T4, but much more T4 than T3. The rest of the T3 comes from "conversion" in peripheral organs, mostly the liver and kidneys, but conversion sites are ubiquitous throughout the body.
The pituitary converts T4 to T3 for its own use, and judges FT3 and FT4 levels based on its own conversion.
The enzyme that catalyzes the conversion of T4 to T3 is 5'-deiodinase (pronounced five prime d-i-o-din-aze). In PRTH, the pituitary is lacking 5'-deiodinase. It can't convert T4 to T3, so it "thinks" the rest of your body is starved for T3 like it is. It's not. Your FT3 and FT4 can be properly adjusted, but TSH doesn't move.
So, in my case TSH has to be ignored, and we have to go by symptoms, FT3 and FT4.
Anyway, this is just something to keep in mind if your TSH continues to be obstinate. What's the range on your FT4? I suspect it's still pretty low in the range, and you're symptomatic, so you still have to raise meds (you are on meds, correct?) and get rid of the rest of your symptoms. Ultrasound is usually the first step in investigating nodules, so your new doctor ought to do that. Antibody testing, definitely.
Hope your appointment with the new doctor went well.
T3 is the "active" form of the thyroid hormones. T4 is the "storage" form. Your body cannot use T4 until it is converted to T3. Normally functioning thyroids produce both T3 and T4, but much more T4 than T3. The rest of the T3 comes from "conversion" in peripheral organs, mostly the liver and kidneys, but conversion sites are ubiquitous throughout the body.
The pituitary converts T4 to T3 for its own use, and judges FT3 and FT4 levels based on its own conversion.
The enzyme that catalyzes the conversion of T4 to T3 is 5'-deiodinase (pronounced five prime d-i-o-din-aze). In PRTH, the pituitary is lacking 5'-deiodinase. It can't convert T4 to T3, so it "thinks" the rest of your body is starved for T3 like it is. It's not. Your FT3 and FT4 can be properly adjusted, but TSH doesn't move.
So, in my case TSH has to be ignored, and we have to go by symptoms, FT3 and FT4.
Anyway, this is just something to keep in mind if your TSH continues to be obstinate. What's the range on your FT4? I suspect it's still pretty low in the range, and you're symptomatic, so you still have to raise meds (you are on meds, correct?) and get rid of the rest of your symptoms. Ultrasound is usually the first step in investigating nodules, so your new doctor ought to do that. Antibody testing, definitely.
Hope your appointment with the new doctor went well.
Thank you Goolarra for your helpful response.
I don’t think the thyroid antibodies tests TPab and TGab have been done on me.
My Dr. is really old and it was hard enough to get her to order the FreeT4 test (that I read was actually more useful than the Total T4 that she kept getting tested) neither have I been tested for nodules yet.
I am seeing a different Dr. on Monday and hope she is more up-to-date with her knowledge and patient friendly. I am going to ask for the antibodies test and the nodule exam (although I am concerned about the risks of a radioactive Iodine test I’d rather have the ultrasound) as I am worried "the choking while eating" means I may have nodules.
My vitamin D levels did come really low in the April 2010 test. I have started the Vitamin D supplement and being out in the sun at least an hour everyday (whenever the Sun obliges)
Yes I would like to know more about the PRTH and your experience with hypothyroidism in general. Also I will post more after I get back from the Dr on Monday.
Thank you.
I don’t think the thyroid antibodies tests TPab and TGab have been done on me.
My Dr. is really old and it was hard enough to get her to order the FreeT4 test (that I read was actually more useful than the Total T4 that she kept getting tested) neither have I been tested for nodules yet.
I am seeing a different Dr. on Monday and hope she is more up-to-date with her knowledge and patient friendly. I am going to ask for the antibodies test and the nodule exam (although I am concerned about the risks of a radioactive Iodine test I’d rather have the ultrasound) as I am worried "the choking while eating" means I may have nodules.
My vitamin D levels did come really low in the April 2010 test. I have started the Vitamin D supplement and being out in the sun at least an hour everyday (whenever the Sun obliges)
Yes I would like to know more about the PRTH and your experience with hypothyroidism in general. Also I will post more after I get back from the Dr on Monday.
Thank you.
smilerdeb and louscha, Thank you for your response.
I was diagnosed with hypothyroidism in sept 2008. I had all the symptoms associated with hypothyroidism- feeling extremely tired, depression, constipated for days, dry skin, falling hair, swollen feet, palpitations, even black outs, poor concentration, loss of memory, joint pains, a visible tiny lump on my gland. My blood tests revealed a TSH of 72.
My energy started to come back although not fully there yet but other symptoms like dry skin, palpitations, swollen feet, the lump on the neck, joint pains, constipation have disappeared.
In April 2009 my TSH test showed 15 and this april its 20 with a normal free T4. The symptoms that I still have with albeit reduced intensity are lack of concentration with my studies, poor memory with numbers, low vitamin D levels, still not as energetic as I used to be pre-hypothyroid, feeling weepy somedays with no apparent reason, a choking sensation while trying to swallow food happening about once every couple of months.
Does this mean I have moved from being hypothyroid to subclinical hypothyroidism ?
Should I get more tests done to rule out my pituitary or autoimmune conditions ?
I was diagnosed with hypothyroidism in sept 2008. I had all the symptoms associated with hypothyroidism- feeling extremely tired, depression, constipated for days, dry skin, falling hair, swollen feet, palpitations, even black outs, poor concentration, loss of memory, joint pains, a visible tiny lump on my gland. My blood tests revealed a TSH of 72.
My energy started to come back although not fully there yet but other symptoms like dry skin, palpitations, swollen feet, the lump on the neck, joint pains, constipation have disappeared.
In April 2009 my TSH test showed 15 and this april its 20 with a normal free T4. The symptoms that I still have with albeit reduced intensity are lack of concentration with my studies, poor memory with numbers, low vitamin D levels, still not as energetic as I used to be pre-hypothyroid, feeling weepy somedays with no apparent reason, a choking sensation while trying to swallow food happening about once every couple of months.
Does this mean I have moved from being hypothyroid to subclinical hypothyroidism ?
Should I get more tests done to rule out my pituitary or autoimmune conditions ?
I have read it might be subclinical hypothyroidism which means that the thyroid needs a LOT of Thyroid Stimulating Hormons to work properly (providing normal T4 and T3). Do you have hypothyroidism symptoms? (fatigue, cold skin, weight gain, hair loss, thin nails...)
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Over the next year, after starting T4 meds, all my symptoms went away, but my TSH remained around 20 (and still is...I know, you have to spell out the t-w-e-n-t-y so we don't think you forgot the decimal point!). I was feeling well, but my PCP kept telling me to "take more thyroid". I did as she said for a while, but got to the point where I felt that something was very wrong with this approach. I was taking more and more meds just to get my TSH "right" and it wasn't changing how I was feeling (I felt well, but I was made to think that I didn't know what "well" felt like anymore).
Sometimes, when my FT3 and FT4 go down, so does my TSH, sometimes they all go up together, and sometimes they actually behave properly.
Long story short (why start now?), I finally saw an endo, who diagnosed me with Hashi's and pituitary resistance to thyroid hormone (PRTH). If you're interested in more info on that, I'll be happy to tell you what I know. The PRTH is why my TSH is always around 20 and will never come down.
However, that said, you say that you still don't have all your energy back, so your FT4 level, though "in reference range", might be a little on the low side for YOU individually. Do you have the actual results of recent FT4s and the refernce range for it? Have they been testing FT3 also?
Also, are you supplementing vitamin D? D deficiency can cause or exascerbate many of the symptoms you list.
Are you taking thyroid meds? If so, which and at what dose?
It would be a good idea to have antibodies tested for autoimmune disease (Hashi's). Make sure they test both TPOab and TGab as some of us with Hashi's have one or the other and some both.