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Severe Low TSH Normal Free T3 and T4
I have been on synthroid for about 15 years.  I am on 150mg at the present time.  My TSH levels are extremely low 0.016, but Free T 3 and Free T4 are normal levels. Am I on too much synthroid?  This is really confusing to me!  Can you please help? Am I considered Hypo or hyper thyroid?
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Hypo or hyper thyroidism should be defined by symptoms, not by results from blood tests.  This is especially true for TSH, which correlates very poorly to symptoms.  The best correlation, and the most important test, is free T3, with free T4 a distant second.  

My opinion is that the best way to treat a thyroid patient is to listen carefully to symptoms, and test and adjust the free T3 and free T4 levels as required to achieve a Euthyroid state, which means neither hyper nor hypo symptoms.  Many patients will have suppressed TSH results in order to get free T3 and free T4 to a level to alleviate symptoms.  Only you should  determine if you are taking too much synthroid,  by deciding if you are experiencing hyper symptoms.

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Thank you so much for the the information!  Sooo..that being said, I can assume that if the symptoms are better, it is not dangerous to have extremely low levels of TSH when the T3 and T4 are at optimal levels.  
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When you think about it, TSH is a Pituitary hormone that's purpose is to signal the thyroid glands to increase/decrease output of thyroid hormone.  Having a low amount of TSH doesn't do anything to the body.  It is only an indicator  of the level of T4 and T3 in the blood.  And in fact, only the free (unbound portion) of these hormones, free T3 and free T4, are biologically active in the body.   Free T3 is the most active.  It is four times as potent as free T4.  
So, unless a low TSH is signalling excessive amounts of the "Frees", confirmed by free T3 and free T4 tests, and by hyper symptoms, than there would be no concern.  My opinion is that tests for the "Frees" are much more reliable and useful for thyroid patients that TSH.
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That makes sense to me!  I really do appreciate you taking the time to help.  I'm sure that I am not the only person on here that has been confused by this subject.  You have made it simple and I am greatful for that.
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I have a different perspective than the one received re TSH's only function being to stimulate the thyroid to make more hormones.

TSH is very, very important for improving or upregulating the number of channels that absorb iodine into various tissues including breasts and ovaries.  And getting iodine into these tissues helps to protect them from environmental toxins and has shown to reduce cysts and other risk factors for developing cancer.

So, it IS important to monitor TSH and to keep it in the normal range.  Iodine will also improve TSH levels if they get too low.

All the best,
Dr. Alexander Haskell
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I would love to learn more about this.  Do you have any articles about this I can look at?  I had a partial thyroidectomy and the 1/3 left is atrophied.  I take dessicated thyroid medicine so my TSh is always very very low, usually way below 1.  If I do not have a functioning thyroid do I have to be worried about iodine deficiency?
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231441_tn?1333896366
Hello,

I am also interested in this.

However many of us here now find that our TSH is extremely low (after years of being on thyroid med), regardless of where our FT3 and FT4 are.  Ie. My TSH is below detection range, but my FT3 and FT4 are well within the reference range.  Reducing my thyroid meds does not increase my TSH, it only decreases my FT3 and FT4.  We have tried. TSH only slowly increases when levels are below range (and by that time I am also feeling extremely bad).  

Btw I do have a pituitary microadenoma.  Previously had high prolactin levels which were supprssed with bromocriptine.  Don't know if there was any other effect from this.

Anyway, given what you've said, what would you recommend in this circumstance?

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So abnormally low TSH (in the face of 'normal' FT3 and FT4) could represent an iodine deficiency?
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Yes, please, cite links to studies supporting your hypothesis.

Also, please coment on HIGH TSH.  Is more better?  

Please explain how "iodine levels will 'improve' TSH levels if they get too low".
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Sorry to have not checked in until now to give a little more feedback on a previous statement.
Again, TSH stimulates channels to absorb iodine into various tissues and iodide into thyroid cells.  Every medical physiology book calls the channels in thyroid cells, iodine traps, even though they absorb iodide.
The other channels are known as NIS or Sodium Iodine Symports.  TSH upregulates and increases the number of these channels, and so TSH is important.  Iodine has many important qualities when it comes to protecting breast tissue from environmental toxins and is known to reduce breast cysts and what's called benign breast disease.  
This is why iodine and iodide will cause an increase in TSH because the body wants to store these two valuable trace minerals.
More on this... I'll try to stay in touch more frequently.  You might like to visit my site which is on a thyroid condition known as Hashimoto's.  I'll be uploading some educational videos around February 10th, 2010.
Thanks
Dr. Haskell
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Hello!

I just recently was able to get my endo to check my free t3 and t4 levels after four years, They showed my levels to be normal but my tsh abnormally low (.02). Four years ago, I was also diagnosed with a complex ovarian cyst which began to shrink once another doctor, who practiced holistic medicine, placed me on 50 mgs. of iodoral for a month, reducing it to 12.5 mgs. for the rest of his treatment. But upon seeing my endo, he took me off it because he discovered that I had Hashimoto's. Needless to say, the complex cyst has returned and has begun to grow larger.

I don't know what is the lesser of two evils. Do I begin using iodine again to fix the cyst or do I let the cyst grow and treat the Hashimoto's?  My endo believes iodine exacerbates my hypothyroidism. Please help!
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How do I get my endocrinologist to agree with you?  I know how I feel and it was wonderful having enough energy and drive to enjoy life.  I smoke, which apparently lowers TSH and raises FT4 and Ft3, too.  Help!  I'm crashing.
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