PTH and Hypocalcemia: As shown in Table 1, an increasing number of potential risk factors for postoperative hypocalcemia, including age, sex, serum magnesium, serum vitamin D, parathyroid injury (e.g., contusion, impaired blood supply, inadvertent removal of the parathyroid glands), and the parathyroid hormone (PTH) level, have been investigated in recent years (Qin et al., 2020).