Liu C, Tang L, Goel P, et al. - Researchers conducted a retrospective cohort study of 100 patients with primary hyperparathyroidism who underwent parathyroidectomy as the primary treatment modality in order to predict the severity of hypocalcemia after parathyroidectomy or thyroidectomy. In addition, they sought to stratify patients into groups with different levels of risk for developing severe hypocalcemia, so that close monitoring and earlier interventions could be undertaken in higher-risk patients. The most significant predicting factor for the severity of postoperative hypocalcemia was the percentage of reduction from preoperative PTH level to the lowest PTH level after the removal of the abnormal gland(s). A mathematic regressional correlation was noted between them. They generated a formula to quantify this linear relationship between them, and the nadir calcium can be calculated as Ca_nadir = Ca_preop*[1−0.35*(PTH_preop−PTH_intraop)²/PTH² _preop], where Ca_nadir = the lowest postoperative calcium level, and PTH_intraop = PTH level 15 minutes after removal of the abnormal gland, with the value of R² > 0.7. They primarily tested the formula in this patient population with good reliability. These foindings suggest the utility of the highest preoperative, lowest postoperative, and change in PTH level in reliably calculating the trend of postoperative calcium level. The calculated result from the formula may assist in the decision to pursue early interventions.