I am 69 years old male. For the last 6 years hypothyroid. I am taking thyroxin 50 mg daily at 6 am empty stomach. On regular test oncea tear now the readind tsh has increased from 5.1 to 7.6. What is the reason for the increase. Any food restrictions. I had myocardiac infraction in may 2001 and under medical management taking met xl, vasovin, lipi-zand clopilet. I have potassium 5.9 taken recently. What is thereason for increase tsh 4.