Hello, Thanks for trusting Healthcaremagic! I have gone through your query and I can understand your concerns. Thyronorm is the brand name of a drug called levothyroxine. it is almost similar to natural thyroid hormones produced by our thyroid gland. Thyronorm does not cause high cholesterol. In fact thyronorm increases our basal metabolic rate and thus lower blood choslesterol level. Undetected hypothyroidism can cause high cholesterol,do a thyroid function test and make sure that your thyroid status is fine. Your hypercholesrelemia might be due to some other reason. Do fasting lipid profile. Since your cholesterol is very much high,you have to start cholesterol lowering agents like atorvastatin at the earliest. Hope I have answered your query. Regards. Dr.Shinas