Last October I went to see GP as memory was really bad & i felt tired etc. I was taking 150mcg of thyroxine. My blood test showed a suppressed TSH but T4 was 16.7 (9.00-26.00). I asked if I could try & get my T4 higher as not even midway, she agreed to see if this helped. I moved up to 175mcg of thyroxine & my symptoms have improved. Moving on to now, the tiredness, awful dry skin on my feet & the need to go to bed prompted me to go back to GP & latest blood test revealed I'm Vitamin D deficient & I'm being treated for that but when I saw my blood test results my TSH was still suppressed but my T4 has dropped slightly to 16.3. I've read a lot on this forum that people feel better when T4 is at the top end, how can I achieve this as just increasing my thyroxine isn't working???