How consistent should your TSH levels be?

[adorkable]

I have been poked more than a dozen times in the last year, sometimes with months in between tests.  The TSH levels always alternate from high-normal to high.  My doctor keeps having me repeat the test even as she looks at the results in my record.  On a previous visit I was told that if my levels were high again I would be put on a low dose regimen but the levels came back high and she, once again, told me I should be tested again.  Both my mom and sister take medication for their hypothyroidism.  

What is considered normal fluctuation for TSH levels? Is the fluctuation bad for my thyroid?  Like weight gain/loss is for your heart?  I gain and lose 40lbs almost every other year.  Is this related?  Is taking medication while it's normal/high-normal bad for me?

These are questions I've asked my doctor before but I don't seem to get straight answers and am filled with so much information each visit that I don't realize I've been duped until I'm laying in bed at night, worrying.  My husband and I want to have children but I need to make sure I have my health issues (thyroid? -> obesity -> hypertension -> infertility) in check, first.

Any insight would be very greatly appreciated!

[Smilerdeb]

Good posting gimel !

[gimel]

Rather than trying to address what are normal levels of fluctuation in TSH test results, I'd like to give you some info on TSH and why it is not the definitive test for being hypo.  TSH is a pituitary hormone that is affected by so many variables, including the time of day when blood is drawn, that it is inadequate as a diagnostic.  I say this even though most doctors seem to have "The Immaculate TSH Belief".  Seven years after the AACE recommended changing the reference range for TSH to .3 - 3.0, most labs and doctors seem to still cling to the old range of .5 - 5.0.  

At best TSH should be considered as an indicator, to be considered along with more important indicators which are symptoms, as well as levels of the actual, biologically active thyroid hormones, free T3 and free T4.   Free T3 is actually the most important because it is four times as active as FT4, plus FT3 correlates best with hypo symptoms.  By comparison, TSH correlates very poorly with hypo symptoms.

So in my opinion the very best way to treat a thyroid patient is to test and adjust the levels of FT3 and FT4 with whatever medication is required to alleviate symptoms, without being constrained by resultant TSH levels.  Symptom relief should be all important.  From what we hear from many members this frequently requires that FT3 is adjusted into the upper part of its range and FT4 is adjusted to at least midpoint of its range.

The most difficult part of all this is to find a good thyroid doctor that will test for FT3 as well as FT4 and TSH, and will treat you in this manner.