Fig. 3. Intraoperative parathyroid hormone (PTH) dynamics in a patient where the intraoperative >50% PTH decrease criterion is not met at 10 minutes after parathyroid gland excision or if the decline dynamics are equivocal (e.g., borderline PTH drop at 50%). In the majority of patients, the “>50% intraoperative PTH drop” criterion is achieved with an additional 20-minute PTH measurement that excludes a false negative result, accurately predicts postoperative success and prevents unnecessary bilateral neck exploration. Dotted line shows time of gland excision.