Having a cold or some other “illness” is not a reason to cancel your parathyroid operation. Having parathyroid problems will effect your immune system and can actually increase your risk of getting colds or the flu.
Do not worry about this kind of stuff. If you are healthy enough to get here, you are healthy enough to have an operation. Do not cancel or delay your operation because you have a cold, or a bout of gout, or some other minor illness.