Pitfalls of intraoperative quick parathyroid hormone monitoring and gamma probe localization in surgery for primary hyperparathyroidism

Abstract

Hypothesis: Intraoperative quick parathyroid hormone (qPTH) monitoring and gamma probe (GP) localization greatly aid the surgeon.

Design: Prospective case series of patients undergoing parathyroidectomy (PTX) with preoperative localization studies, operative data (including intraoperative qPTH values and GP localization), and outcomes. Follow-up was complete (mean, 4.2 months).

Setting: University teaching hospital.

Patients: We studied 57 consecutive patients with primary hyperparathyroidism from December 1, 1999, through November 30, 2000. Of these, 51 underwent first-time PTX, and 6, reoperative PTX (rePTX).

Main outcome measures: Cure rate and morbidity after PTX or rePTX; sensitivity and accuracy of preoperative localization studies; prediction of cure from results of qPTH monitoring (comparing Nichols [>50% fall from the highest baseline level and lower than the lowest baseline] or normal-limit [>50% fall from first baseline level and lower than upper limit of the reference range] criteria); and value of GP localization.

Results: Patients were cured in 50 (98%) of 51 PTX and 6 (100%) of 6 rePTX for single adenomas (n = 49), double adenomas (n = 4), and multigland hyperplasia (n = 3). Nichols criteria for qPTH monitoring correctly categorized 45 (92%) of 49 cured single adenomas 10 minutes after excision. Only 35 (71%) of these adenomas were correctly categorized as cured by means of the normal-limit criteria. In double adenomas, both sets of criteria in the 10-minute samples indicated unresected glands in only 2 of 4 cases. Preoperative sestamibi parathyroid scans correctly localized 38 (76%) of 50 single adenomas. The GP was used in 54 of 57 cases. All adenomas measured greater than 20% of background ex vivo, but 6 thyroid nodules also measured greater than 20% ex vivo. In double adenomas, the GP helped locate the second adenoma in only 1 of 4 cases. The GP was graded as crucial in 2 cases with dense scar (both rePTX), helpful in 12 (22%) of 54 cases (particularly in retroesophageal glands), confirmatory in 32 (59%), and not helpful in 8 (15%). The GP helped localize 3 (43%) of 7 glands not seen on sestamibi parathyroid scans.

Conclusions: Intraoperative qPTH monitoring confirmed cure in most cases. For single adenomas, use of the Nichols criteria for qPTH assessment allowed more accurate and faster confirmation than the normal-limit criteria. The GP was less useful but was crucial in 2 rePTX cases; it was not specific for parathyroid tissue. Both techniques have potential pitfalls that could result in surgical failure.