Thank you for answering me on Feb. 12. My Dad has been on levothyroxine for 12-14 years and has been having slight cognitive problems (memory) until recently ( now a 10 second loop) . I had his endocrinologist put him on cytomel (5mcg) for about a year and increase his 100mcg levothyroxine to 125 mcg too that year. His TSH went below norm and T4 went to the high range...and didn't help memory. I'm trying the reverse now so went from 100mcg T4 (OK after month) to 71mcg. to 57 mcg(now for month). Is it ok to take 4 out of 7 days 100mcg. to have weekly daily amount 57mcg. or should Dad be on daily pill of 50 or 60 mcg? I know no one is studying this, but since thyroxine was used to control cholesterol before statins, could thyroxine have anticholinergic properties for some people like statin meds? Dad has all the symptoms and it started 12-14 years ago according to my Mom.