A “defined baseline” in PTH monitoring increases surgical success in patients with multiple gland disease

Background Parathyroid hormone (PTH) monitoring with a quick intact PTH (QIPTH) assay is used in minimally invasive exploration for primary hyperparathyroidism (PHPT) in order not to miss multiple gland disease (MGD). Controversy exists on which criterion is most reliable to predict cure. Methods QIPTH values of 310 consecutive patients (single gland disease [SGD]: n = 289; MGD: n = 21) with sporadic PHPT were analyzed using 3 different criteria: “Vienna Criterion”: ≥50% decay from a defined “baseline” level (right after induction of anesthesia before skin incision) 10 min after excision. “Miami Criterion”: ≥50% decay from highest (preincision or preexcision) value 10 min after excision; “Halle Criterion”: decay of the PTH- level to less than or equal to 35 pg/mL within 15 min after excision. Results The “Vienna” and “Halle Criteria” correctly detected MGD in 19 (91%) and the “Miami Criterion” in 12 (57%) of 21 patients. Incorrect prediction of incomplete excision occurred in 22 patients (8%) with SGD, using the “Vienna Criterion” (“Miami Criterion”: 2%, “Halle Criterion”: 29%). All of these were recognized intraoperatively from unintended intraoperative manipulation (n = 18), technical failure (n = 2), or borderline increased PTH values (n = 2), and they did not lead to bilateral exploration. Analyzing patients with SGD and MGD, accuracy and specificity were 92% and 89% for the “Vienna Criterion,” 93% and 54% applying the “Miami Criterion,” and 72% and 89% using the “Halle Criterion.” Conclusion Strict definition of a PTH “baseline level” (“Vienna Criterion”) improves intraoperative diagnosis of MGD, thus reducing reoperations and increasing long-term cure.