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Published on: August 17, 2022
A spike in parathyroid hormone during neck exploration may cause a false-negative intraoperative assay result
G P Yang1, S Levine, R J Weigel
1Department of Surgery, Stanford University School of Medicine, Stanford, CA, USA.
Insights
False-negative rapid intraoperative parathyroid hormone (IOPTH) assay results can occur due to hormone spikes during adenoma mobilization. Adjusting the IOPTH sampling protocol is crucial for accurate intraoperative parathyroid hormone monitoring.
Area of Science:
- Endocrinology
- Surgical Oncology
- Clinical Chemistry
Background:
- Primary hyperparathyroidism is often treated with surgical excision of parathyroid adenomas.
- Intraoperative parathyroid hormone (IOPTH) monitoring is a valuable tool to confirm successful adenoma removal.
- Potential inaccuracies in IOPTH assays can lead to suboptimal surgical outcomes.
Purpose of the Study:
- To investigate the hypothesis that transient parathyroid hormone (PTH) spikes during adenoma mobilization can cause false-negative IOPTH results.
- To identify potential causes of false-negative IOPTH assay findings during parathyroidectomy.
- To refine IOPTH monitoring protocols for improved accuracy in detecting adequate parathyroid tissue excision.
Main Methods:
- Retrospective analysis of a case series of ten patients undergoing neck exploration for primary hyperparathyroidism.
- Intraoperative parathyroid hormone (IOPTH) levels were monitored using a specific sampling protocol, including measurements at incision, during adenoma mobilization, and 10 minutes post-resection.
- Parathyroid hormone half-life was calculated, and adequacy of excision was confirmed by IOPTH levels and postoperative serum calcium.
Main Results:
- Nine patients demonstrated an appropriate decline in IOPTH levels, with a mean PTH half-life of 3.9 minutes.
- A significant spike in IOPTH was observed during adenoma mobilization in one patient, increasing from 95.5 pg/mL to 751 pg/mL.
- A false-negative postexcision IOPTH value was recorded in a patient with a confirmed solitary adenoma, attributed to an undetected spike during dissection.
Conclusions:
- Transient spikes in parathyroid hormone (PTH) levels during adenoma mobilization can lead to false-negative intraoperative parathyroid hormone (IOPTH) assay results.
- Existing IOPTH sampling protocols may miss these spikes if baseline measurements are taken early in the procedure.
- The study led to an updated IOPTH assay protocol, now including measurements at incision, complete adenoma removal (time zero), and 10 minutes post-excision.
Hypothesis:
We hypothesize that false-negative results using the rapid intraoperative parathyroid hormone (IOPTH) assay can be caused by spikes in the level of parathyroid hormone that occur during mobilization of the adenoma.
Design:
Retrospective analysis of a case series.
Setting:
University tertiary care center.
Patients:
Ten consecutive patients with primary hyperparathyroidism.
Interventions:
All patients underwent neck exploration with IOPTH monitoring. Using a sampling protocol described in the literature, IOPTH values were checked at the time of incision, during mobilization of the adenoma, and 10 minutes after resection of the adenoma.
Main Outcome Measures:
Patients were evaluated for adequate parathyroid tissue excision as determined by IOPTH levels and examination of ipsilateral glands. All patients had normal serum calcium values documented postoperatively. Parathyroid hormone half-life was calculated assuming first-order kinetic decay.
Results:
Nine patients had an appropriate decline in IOPTH with a mean +/- SD parathyroid hormone half-life of 3.9 +/- 1.08 minutes. Mobilization of the adenoma resulted in a spike in the IOPTH value, with 1 patient's value increasing from a baseline of 95.5 pg/mL (10.1 pmol/L) to 751 pg/mL (79.1 pmol/L). Another patient who was confirmed to have a solitary adenoma had a false-negative postexcision value. A spike in IOPTH that occurred during neck dissection was not detected by the sampling protocol and explains the false-negative value. A literature review revealed that most protocols check baseline values early in the operation and are at risk for false-negative results due to a spike from mobilization of the adenoma.
Conclusions:
These data demonstrate that false-negative IOPTH assay findings can result from a spike in parathyroid hormone level during exploration, which may go unrecognized if baseline values are measured during the early stages of mobilization of the adenoma. We have altered our assay protocol and have begun measuring IOPTH at the time of neck incision, at the time the adenoma is completely removed (time zero [t(0)]), and 10 minutes after excision.
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