Severe Low TSH Normal Free T3 and T4

[teresa3100]

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?

[gimel]

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.

[teresa3100]

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.  

[gimel]

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.

[teresa3100]

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.