What causes really high tsh levels?

[Kris1086]

I was placed on .05 of levathrozine a year ago. I'm getting ready for weight loss surgery so in feb they did blood test on me that came back a little high my tsh was 5.7 so they wanted me to get cleared by my regular dr. I went in last Thursday for another test Monday morning my dr called me tellin me she needed me back in that day because my tsh was 71.2 but my t4 was normal she believed it was just a lab mistake so Monday I did another test and got a call saying that it was now 45 and still t4 was normal. She thinks it's bc I was taking it with other meds which I'm now now. So I'll retest in 6 weeks but I started thinking okay but why did it go down from 71 to 45 I hadn't changed anything yet. I'm very worried bout this. Is this normal? 5.7 in feb and 71 last wk and 45 this Monday?

[gimel]

I am not familiar with the thyroid med you mention.  Could it be levothyroxine, or are you in another country where T4 med has a different name?  

TSH is a pituitary hormone that is affected by so many things that at best it is only an indicator, to be considered along with more important indicators such as symptoms and also levels of the biologically active thyroid hormones, Free T4 and Free T3.  So please tell us about symptoms that you have and also post results and reference ranges from any thyroid tests you have had besides TSH.