This study shows that the measurement of intact PTH levels obtained from aspiration of tissue excised during surgery for hyperparathyroidism is highly specific for parathyroid tissue. The additional cost for the tissue assay when intraoperative monitoring of serum intact PTH level is used is less than the cost of a frozen section analysis. The authors state that this would allow a more selective use of frozen section analysis during parathyroid surgery. However, frozen section analysis is rarely needed when a localized hyperfunctioning gland with a typical gross appearance is removed and an appropriate decrease in serum intact PTH is seen. This is particularly true if the hyperfunctioning gland is localized to the same anatomic site, shown by both technetium Tc 99m sestamibi scintigraphy and ultrasonography. A typical hyperfunctioning parathyroid gland is soft and reddish or tan. However, all hyperfunctioning glands do not have this typical appearance. A frozen section is needed to facilitate parathyroid tissue identification when the gross features of the resected gland are atypical. It is not unusual for a hyperfunctioning parathyroid gland to have an atypical gross appearance. This can be caused by a parathyroid carcinoma or more commonly by an atypical benign hyperfunctioning parathyroid gland. It is occasionally difficult to distinguish by gross appearance alone an atypical hyperfunctioning parathyroid gland from a lymph node, thymus tissue, or ectopic thyroid tissue. Even experienced pathologists occasionally have difficulty differentiating an atypical hyperfunctioning parathyroid gland from thyroid tissue. Staining for the presence of thyroglobulin, which is difficult to perform given the time frame for performing frozen section examination, is sometimes the only feasible method for differentiating between thyroid tissue and parathyroid tissue. The aspiration of resected tissue for PTH may be helpful even if there is an appropriate fall of serum intact PTH indicating correction of hyperparathyroidism after resection of a suspected adenoma. Extensive dissection may have compromised the blood supply of the adenoma resulting in an appropriate decrease of serum intact PTH without resecting the adenoma. It may also be helpful if there is no acceptable decrease in serum intact PTH levels after removing an atypical lesion. The lesion removed may represent the only hyperfunctioning parathyroid gland, but the patient will have an appropriate but delayed drop of serum intact PTH. Confirmation by tissue aspiration that the atypical lesion removed was parathyroid tissue allows the surgeon to obtain a delayed intact serum PTH level before proceeding with further exploration.
Monchik JM. Applicability of Tissue Aspirate for Quick Parathyroid Hormone Assay to Confirm Parathyroid Tissue Identity During Parathyroidectomy for Primary Hyperparathyroidism—Invited Critique. Arch Surg. 2005;140(2):150. doi:10.1001/archsurg.140.2.150