Thyroid nodules are very common, and most of the time they are completely benign. If there is a concern for cancer, then it makes sense to have the nodule biopsied before undergoing parathyroid surgery, since the thyroid operation can be done at the same time as the parathyroid.

If your nodules all appear benign on ultrasound (the best imaging study for thyroid nodules) then getting a biopsy is probably not necessary. If there is some concern for malignancy - that is, if the nodule is growing quickly or has certain suspicious features like microcalcifications, then I would recommend getting it biopsied before parathyroid surgery. The biopsy is a fine needle aspiration (FNA) biopsy, done with a thin needle stuck into the nodule. These are very good at diagnosing thyroid cancer.

If you do have thyroid cancer, it is treatable. The main treatment for most thyroid cancers is removal of part or all of the thyroid. This can be done at the same time as your parathyroid operation, but it helps if your surgeon knows what to expect. If the nodule shows cancer on a biopsy, then your surgeon will probably need to do more imaging studies prior to surgery in order to assess whether the cancer has spread to any lymph nodes. Your surgeon will be able to take care of that during the operation, but needs to know about it first.

If your thyroid nodules are benign, you may not need them to be removed. Sometimes, removing a benign thyroid nodule is very easy, and can be done safely without adding significant time or risks to the operation. Other times, removing thyroid nodules can be much more involved, and increase the risks of the operation. Some people have thyroids that are essentially replaced by benign nodules. Removing all of the nodules will mean removing the entire thyroid. This increases your risks of surgery, and also means that you will need to take thyroid hormone for life.

For benign nodules, I will typically remove them if they are large (2 cm or larger) or if there is something suspicious about the nodule, even if the biopsy was negative. Tiny benign nodules are very common and can be ignored.