Hi, I have had an under active thyroid now for over 30 years, since I was 20. I never feel 100%, tired, find it difficult to loose weigh etc despite being in thyroxine. When I have my blood tests my G.P informs me that my results are "within the correct range". My question is how do you know where in the range you are likely to feel better? If I am on the lower part, which I am the only way to be further up the range would be to increase my medication which they won't do.