In our second analysis, we aimed to find out whether low preoperative 25-OHD level affected the accuracy of single qPTH in predicting hypocalcemia by comparing the AUC of PTH-SC when 25-OHD <15 ng/mL with the AUC of PTH-SC when 25-OHD ≥15 ng/mL. This evidence concerns the gene PTH and Hypocalcemia.