I am a 53 year old female.Having had thyroidectomy some 23 years ago and being fine, apart from one glitch about 5 years ago, on 150 mcg of thyroxine ever since, by blood test in October came back with a raised level of 29. My doctor said to reduce to 125mcg, but after 4 weeks of this I felt dreadful! I had no HYPER symptoms on my 150 dose at all. After reducing to 125 for 4 weeks I felt terrible, such fatigue, exhaustion and problems with concentration. My hair became very thin too. A further blood test showed the level now at 20 - still outside the normal range. I could not function feeling so unwell and decided to increase my dose myself a week ago. Since then I have started to feel much better, like my old self. What else could cause this to happen? I am going to a review at my doctor's tomorrow and I just don't want her to insist that I reduce my dose again, as I felt so bad. Could something else be the culprit for this untoward blood result? The previous glitch was the same problem and was rectified when I resumed my usual dose.