I am 58 and have been stabilised on Oroxine ( sodium thyroxine) 150 micrograms daily for about 20 years. My TSH levels have consistently been <0.05 mU/L ( normal range is 0.2-4.0) and free T4 was 17 pmol/L (15-30) with free T3 between 3.9-4.4 pmol. Last week I went to my GP because I was feeling dizzy, havng headaches, nausea and could not tolerate exercise too well. Blood tests showed my TSH the same i.e. below detection levels but free T4 had risen to 19 pmol and bizarrely the normal range had changed to ( 10-20) but I think the lab may have stuffed up! Maybe T4 normal range changes with age- Does anybody know? Free T3 had also risen to 5.1 but that normal range had remained constant at (2.8-6.8). Anyway - my question is - WHAT TO DO ABOUT THE RISE IN BLOOD PRESSURE? I'm 47 kg and exercise almost every day - I do spin 4-5 times per week plus weights and I'm a vegetarian so im fit for my age. This has come as a suprise my some prelim research shows that my kidneys or adrenals could be affected and releasing noradrenaline or angiotensin. can anybody comment?