How long after a thyroidectomy should one wait before beginning synthroid (thyroxine)?

Soon : What the thyroidectomy for? If you had the entire gland removed, and the pathology is non cancerous, you ought to be able to start your thyroid replacement right away. If there was a cancer, there might be a role for treating you with radioactive iodine post operatively. In that case you should wait on starting the thyroid replacement until after the treatment . Ask your surgeon.

Depends: If op for thyroid cancer, wait til they do radioactive iodine ablation if for benign lesions in thyroid, as soon as they know its benign if for hyperthyroidim, within a few days.

Need path results.: Start it ASAP after surgery, as long as you won't have post-op radioiodine therapy (RAI) used for some thyroid cancers-- in which case start AFTER RAI. Usually you don't know if you need RAI for sure until final pathology results come in about a week post-op. Some surgeons start Synthroid (thyroxine) right after surgery and stop if path determines need for RAI. Others will wait for path first, then