Haven't had much appetite and had little nausea and lost a few lbs since total thyroidectomy 1 wk ago. can this happen. on synthroid (thyroxine).?

Synthroid (thyroxine): Synthroid (thyroxine) could cause this; however, it is unlikely since you've only been taking it for a week -- with the exception of the nausea. The anesthesia used for surgery may have some effect. In addition, your body is healing from the surgery and the release of certain hormones may be involve in this as well. Other medication may also contribute ( ie: post surgery antibiotics).

Absolutely: After only 1 week, it is normal to have the feelings you are having now. I tell my patients that it may take 2-3 weeks before they feel almost normal--longer if thyroid hormone levels need further adjusting. Hang in there and be patient--it is still very early in your healing process.