Abstract
Objectives
The aims of this study were to (1) describe a false-positive result using a highly sensitive intraoperative parathyroid hormone (PTH) assay in an adult patient with primary hyperparathyroidism and (2) discuss the potential pitfalls of revision parathyroid surgery and the implication of various localization techniques described in the literature.
Methods
A case report is described from a tertiary care university hospital. A literature review detailing diagnostic tools used to improve outcomes in parathyroid surgery is presented. The potential inaccuracies of intraoperative PTH assays are discussed.
Results
We present a 71-year-old woman with primary hyperparathyroidism who was referred to our institution for revision surgery. The patient had preoperative sestamibi imaging that localized a right inferior parathyroid lesion. Intraoperatively, a specimen consistent with parathyroid tissue was removed and sent for frozen section. The intraoperative PTH levels were noted to decrease from 154 pg/mL (preincision) to 28 pg/mL (20 minutes postexcision). The frozen section results were consistent with a lymph node. This stimulated a 4-gland exploration, which confirmed normal left superior and inferior parathyroid glands. A 1.5-cm right retroesophageal parathyroid was subsequently discovered and excised. Final intraoperative PTH levels were 20 pg/mL.
Conclusion
Rapid PTH assays have become the mainstay of parathyroid surgery at many institutions; however, despite their accuracy, false-positive results are known to occur. We present a case of an inaccurate decline in intraoperative PTH and use this case report as a means to highlight some potential pitfalls of the test.
1
Introduction
Intraoperative parathyroid hormone (PTH) assays have been well established as a useful adjunct in the focused surgical treatment of parathyroid disease . Multiple criteria that attempt to prevent unnecessary surgical exploration while simultaneously limiting false-positive results (an inaccurate decline in intraoperative PTH despite persistent disease) have been developed.
Although most false-positive results are a consequence of multiglandular disease, laboratory inaccuracies have also been a historical culprit, stimulating the development of newer, more accurate assays .
Despite the accuracy of new rapid PTH assays and the abundant documentation of well-established criteria, which can be used intraoperatively to localize parathyroid disease, inaccurate declines in PTH are still known to occur . We present a case of an inaccurate decline in intraoperative PTH after the removal of nonendocrine tissue in a patient with a persistent parathyroid adenoma. To our knowledge, no similar report exists in the otolaryngology literature. We use this case report as a means to review the current literature and to present a scenario that highlights the necessity for sound surgical judgment in an era of highly accurate laboratory assays.
2
Case report
A 71-year-old woman with a history of primary hyperparathyroidism was referred to our institution to be evaluated for revision parathyroidectomy. Before presentation, the patient had undergone a sestamibi study that localized a right inferior parathyroid lesion. She was taken to the operating room at an outside institution, and a lesion was documented as having been excised from the position of the right inferior parathyroid. Postoperatively, the patient remained hypercalcemic, and a follow-up sestamibi scan demonstrated a persistent abnormality in the right inferior position.
Upon presentation to our institution, the patient remained hypercalcemic, and her PTH levels remained elevated (150 pg/mL). The decision was made to return to the operating room for revision exploration. A preincision PTH was drawn and noted to be 154 pg/mL. Exploration in the expected region of the right inferior parathyroid did not initially reveal any obvious enlarged parathyroid lesions. Ultimately, a nodule measuring approximately 1 cm was noted at the right inferior pole. As a possible candidate for parathyroid adenoma, the specimen was excised from this location and sent for frozen section (FS). After a 20-minute waiting period, the PTH was drawn again and noted to have fallen to 28 pg/mL, an 82% decline in PTH from the preincision level. FS results returned, and the specimen was histologically consistent with a lymph node. To confirm accuracy, the PTH level was repeated after an additional 20 minutes and again found to be 28 pg/mL. A more comprehensive exploration was performed, which involved meticulous dissection of the left superior and inferior positions. Normal-appearing parathyroid glands were noted in each position. Attention was subsequently returned to the right lower parathyroid location. Ultimately, further dissection revealed a large right parathyroid in a slightly retroesophageal position. The gland measured approximately 1.5 cm and had the appearance of a parathyroid lesion. This was removed and sent for FS with results consistent with hyperplastic parathyroid tissue. A final PTH was drawn and noted to be 20 pg/mL (87% decline from preincision PTH) , and the operation was concluded.
All pathologic specimens have been reviewed by a head and neck pathologist who confirm the FS diagnosis. The laboratory assay was dually evaluated and is considered to be correct.
2
Case report
A 71-year-old woman with a history of primary hyperparathyroidism was referred to our institution to be evaluated for revision parathyroidectomy. Before presentation, the patient had undergone a sestamibi study that localized a right inferior parathyroid lesion. She was taken to the operating room at an outside institution, and a lesion was documented as having been excised from the position of the right inferior parathyroid. Postoperatively, the patient remained hypercalcemic, and a follow-up sestamibi scan demonstrated a persistent abnormality in the right inferior position.
Upon presentation to our institution, the patient remained hypercalcemic, and her PTH levels remained elevated (150 pg/mL). The decision was made to return to the operating room for revision exploration. A preincision PTH was drawn and noted to be 154 pg/mL. Exploration in the expected region of the right inferior parathyroid did not initially reveal any obvious enlarged parathyroid lesions. Ultimately, a nodule measuring approximately 1 cm was noted at the right inferior pole. As a possible candidate for parathyroid adenoma, the specimen was excised from this location and sent for frozen section (FS). After a 20-minute waiting period, the PTH was drawn again and noted to have fallen to 28 pg/mL, an 82% decline in PTH from the preincision level. FS results returned, and the specimen was histologically consistent with a lymph node. To confirm accuracy, the PTH level was repeated after an additional 20 minutes and again found to be 28 pg/mL. A more comprehensive exploration was performed, which involved meticulous dissection of the left superior and inferior positions. Normal-appearing parathyroid glands were noted in each position. Attention was subsequently returned to the right lower parathyroid location. Ultimately, further dissection revealed a large right parathyroid in a slightly retroesophageal position. The gland measured approximately 1.5 cm and had the appearance of a parathyroid lesion. This was removed and sent for FS with results consistent with hyperplastic parathyroid tissue. A final PTH was drawn and noted to be 20 pg/mL (87% decline from preincision PTH) , and the operation was concluded.
All pathologic specimens have been reviewed by a head and neck pathologist who confirm the FS diagnosis. The laboratory assay was dually evaluated and is considered to be correct.
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