I have been on Synthroid 0.1mcg for the past 16 years. I have TSH levels drawn every 4-6 months which have always been on the low-normal side with no change in my medication. The last TSH drawn was 0.333 in September. I have been experiencing about 4 days of PAC's/PVC's quite constant, and am wondering if this is due to the low TSH level? I called my PCP who told me to stop the 0.1 mcg of Synthroid and that he was going to change my dosage to 0.75 mcg. If my TSH level is already low, wouldn't lowering my dosage of Synthroid make this level even lower? Are palpitations a symptom of low TSH? I am due to have a repeat TSH in 2 months at which time I will ask the M.D. to add a T3 and T4 (these have not been drawn for some time).....Please advise