Final answer:
The nurse should report tetany and paresthesia immediately.
Step-by-step explanation:
When monitoring a client's postoperative condition after a thyroidectomy, the nurse should report tetany and paresthesia immediately. Tetany is a condition characterized by involuntary muscle contractions and can occur due to hypoparathyroidism, which may result from accidental parathyroid removal during surgery. Paresthesia refers to abnormal sensations such as tingling or numbness and can also be a sign of hypocalcemia, which can occur after a thyroidectomy.