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Low Free T4 Normal Low TSH: Is this really hypothyroidism?
Hi!
I have been having low free T4 (9 pmol/L), but normal although on the lower end TSH (1.69 mIU/L).
My doctor has put me on 75mg/day synthroid, because his diagnostic is hypothyroidism. However, I understand that hypothyroidism is normally associated with low T4, but high TSH.
Based on what I have read, it seems that a low T4 associated with a normal TSH may be linked to issues with the pituary gland (and not the thyroid) or issues with binding agents.
Is hypothyroidism and the use of synthroid indicated in my case?
Thank you,
Frank
I have been having low free T4 (9 pmol/L), but normal although on the lower end TSH (1.69 mIU/L).
My doctor has put me on 75mg/day synthroid, because his diagnostic is hypothyroidism. However, I understand that hypothyroidism is normally associated with low T4, but high TSH.
Based on what I have read, it seems that a low T4 associated with a normal TSH may be linked to issues with the pituary gland (and not the thyroid) or issues with binding agents.
Is hypothyroidism and the use of synthroid indicated in my case?
Thank you,
Frank
COMMUNITY LEADER
frankie_f1... your condition would be called Central Hypothyroidism or secondary hypothyroidism, which means that the thyroid is actually working okay; the problem lies in the pituitary/hypothalamus axis and for some reason there's not enough TSH to stimulate the thyroid. This could be caused by a pituitary adenoma or some other malfunction.
Primary hypothyroidism is when the thyroid, itself fails.
A hypothalamus/pituitary axis problem can affect one or all of the endocrine organs.
The thyroid hormones and iron are a start.
Hypothyroidism doesn't, typically, affect the bladder, as in causing urinary infections or affecting urinary flow... there would seem to be another problem there and whatever that problem is, could well be causing the low libido and ED. Those would be issues for a urologist and should be checked out thoroughly. Untreated bladder/urinary issues or recurring infections can be serious.
Due to the numbness and tingling in your hands, you should also get a vitamin B12 test. Vitamin B12 deficiency can cause numbness/tingling and pain in the extremities. It can also contribute greatly to fatigue.
If your doctor refuses to order further tests, you should find a different doctor, who is willing to test other endocrine hormones to make sure other organs are not affected.
Primary hypothyroidism is when the thyroid, itself fails.
A hypothalamus/pituitary axis problem can affect one or all of the endocrine organs.
The thyroid hormones and iron are a start.
Hypothyroidism doesn't, typically, affect the bladder, as in causing urinary infections or affecting urinary flow... there would seem to be another problem there and whatever that problem is, could well be causing the low libido and ED. Those would be issues for a urologist and should be checked out thoroughly. Untreated bladder/urinary issues or recurring infections can be serious.
Due to the numbness and tingling in your hands, you should also get a vitamin B12 test. Vitamin B12 deficiency can cause numbness/tingling and pain in the extremities. It can also contribute greatly to fatigue.
If your doctor refuses to order further tests, you should find a different doctor, who is willing to test other endocrine hormones to make sure other organs are not affected.
Barb135:
Yes, I have started taking iron supplements.
I have raised potential issues beyond the thyroid, but my doctor is quite convinced that there is no need to further investigate. No tests for free testosterone.
I find that coverage on people having low free T4 and normal-low TSH is quite weak, since it goes beyond the classical case of hypothyroidism. That's why I have turned to community fora.
Thank you,
Frank
Yes, I have started taking iron supplements.
I have raised potential issues beyond the thyroid, but my doctor is quite convinced that there is no need to further investigate. No tests for free testosterone.
I find that coverage on people having low free T4 and normal-low TSH is quite weak, since it goes beyond the classical case of hypothyroidism. That's why I have turned to community fora.
Thank you,
Frank
Were you having any symptoms? With a normal TSH and low T4 it usually due to the pituitary not doing its job but yes it is treated with levothyroxine (synthroid)
COMMUNITY LEADER
frankie_f1... yes, your FT4 is definitely below the limit and indicates hypothyroidism. With a TSH as low as yours, along with the low FT4 and other symptoms you're having, I'm surprised your doctor didn't order more tests.
Have you had Free Testosterone test? The hypothalamus/pituitary axis controls the entire endocrine system and because you have those other symptoms, everything should be checked out.
You "do" need the thyroid hormones, but in my opinion, you also need further testing.
Yes, iron iron is necessary for the conversion of Free T4 to the usable Free T3... you have almost no Free T4, so there's very little to convert and there was no Free T3 tested, so we have no idea about conversion. Did your doctor advise supplementing iron?
Have you had Free Testosterone test? The hypothalamus/pituitary axis controls the entire endocrine system and because you have those other symptoms, everything should be checked out.
You "do" need the thyroid hormones, but in my opinion, you also need further testing.
Yes, iron iron is necessary for the conversion of Free T4 to the usable Free T3... you have almost no Free T4, so there's very little to convert and there was no Free T3 tested, so we have no idea about conversion. Did your doctor advise supplementing iron?
Hi Barb 135:
I have had many symptoms, including fatigue, low libido (including ED and difficulties reaching orgasm), cold extremities, tingling and numbness in hands, arythmia, urinary flow and bladder infections, blurred vision, and low temperature (now often below 36C).
I understand that some of these symptoms can also be linked to the pituitary, such as the low libido (including ED and reaching climax issues) and the blurred vision.
The only test that was carried out for the pituitary is the prolactin, which is normal (12 ug/L).
I have also low Ferritin issues (22 ug/L), which I understand can contribute to hypothyroidism.
With regards to the ranges used by my lab, free T4 is considered normal between 12 and 22 pmol/L and TSH normal between 0.35 and 5 miU/L.
Thank you,
Frank
I have had many symptoms, including fatigue, low libido (including ED and difficulties reaching orgasm), cold extremities, tingling and numbness in hands, arythmia, urinary flow and bladder infections, blurred vision, and low temperature (now often below 36C).
I understand that some of these symptoms can also be linked to the pituitary, such as the low libido (including ED and reaching climax issues) and the blurred vision.
The only test that was carried out for the pituitary is the prolactin, which is normal (12 ug/L).
I have also low Ferritin issues (22 ug/L), which I understand can contribute to hypothyroidism.
With regards to the ranges used by my lab, free T4 is considered normal between 12 and 22 pmol/L and TSH normal between 0.35 and 5 miU/L.
Thank you,
Frank
1 Comments
They need to do away with the TSH level. There is so much talk about how they arrived at such a insane number. I think it should be more like 0.35- 2.5 , even then I think the 2.5 is too high.
COMMUNITY LEADER
What's the reference range for the Free T4? Reference ranges vary from lab to lab and have to come from your own lab report.
Your doctor should also have ordered a Free T3 test... Free T3 is the hormone that's actually used by individual cells in the body, whereas Free T4 must be converted to Free T3.
You're correct that low thyroid hormones, with low TSH, typically, indicates an issue with the hypothalamus/pituitary axis, wherein the thyroid is not receiving adequate TSH to stimulate production of thyroid hormones.
Hypothyroidism is hypothyroidism, and must still be treated with replacement thyroid hormones, whatever the cause. Be thankful you have a doctor that looked at something more than TSH and understands that a pristine TSH doesn't necessarily mean all is well.
The only thing I "might" find fault with, is the dosage of Synthroid... perhaps it's higher than necessary, but provided, you'll be testing in the next few weeks to make sure it's not too much, even that might be okay. Do ask for the Free T3 test next time, since Free T3 is the hormone used by individual cells and correlates best with symptoms.
What, if any symptoms, do you have?
Your doctor should also have ordered a Free T3 test... Free T3 is the hormone that's actually used by individual cells in the body, whereas Free T4 must be converted to Free T3.
You're correct that low thyroid hormones, with low TSH, typically, indicates an issue with the hypothalamus/pituitary axis, wherein the thyroid is not receiving adequate TSH to stimulate production of thyroid hormones.
Hypothyroidism is hypothyroidism, and must still be treated with replacement thyroid hormones, whatever the cause. Be thankful you have a doctor that looked at something more than TSH and understands that a pristine TSH doesn't necessarily mean all is well.
The only thing I "might" find fault with, is the dosage of Synthroid... perhaps it's higher than necessary, but provided, you'll be testing in the next few weeks to make sure it's not too much, even that might be okay. Do ask for the Free T3 test next time, since Free T3 is the hormone used by individual cells and correlates best with symptoms.
What, if any symptoms, do you have?
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