23103 Parathyroid Hormone, Intraoperative Rapid

Parathyroid Surgery Only, IOPTH​

Monitoring parathyroid hormone (PTH) levels during surgery for sporadic primary hyperparathyroidism. To assure that all hyper-functioning parathyroid tissue has been adequately excised and the surgical procedure can be concluded.

Baseline sample/samples prior to surgery may be delivered to the lab by pneumatic tube and will be processed as regular specimen. Specimens drawn during surgery must be immediately hand-delivered to Clinical Automated section for rapid processing and quantitation.
Separate plasma from the blood within 15 minutes of arrival of specimens in the lab. Specimen must be free of particulate matter including fibrin which can interfere with the assay. Plasma specimens for PTH should be kept on ice after collection or maintained at refrigerated temperature as if not processed within two hours PTH is not stable at room temperature and disintegrates at room temperature.

It is important to avoid hemolysis during blood collection by filling the EDTA tube completely and avoiding any shaking of the sample.

Heterophilic antibodies in human serum can react with the immunoglobulins included in the assay components causing interference with immunoassay.

For Tosoh AIA immunoassay method performed at Weston lab, the drug asfotase alfa (Strensiq®), used for the treatment of patients with perinatal/infantile- and juvenile-onset hypophosphatasia (HPP), may cause falsely increased or decreased test results. Test results from patients treated with asfotase alfa should be interpreted with respect to the clinical picture of the patient. Recommend sending test to Marshfield Center lab for analysis by an alternate method.

This test is required for intraoperative surgeries at Marshfield campus. Intraoperative PTH requests must be scheduled with the Marshfield Labs, minimum one week in advance of the scheduled surgery date. A minimum of two serial samples are required (as two separate orders). It includes BASELINE sample and a POST-OP1 sample. Additional orders can be placed depending upon requirement (You are required to notify the Lab if additional POST-OP specimens are needed).

Intraoperative PTH monitoring allows a more focused, less invasive approach to parathyroid exploration without requiring direct visualization of every gland. A bilateral neck exploration requires visualization of all parathyroid glands and excision of enlarged gland(s), with preservation of normally functioning ones. The operative success rate of bilateral neck exploration varies with the experience of the surgeon. The success rate is more than 95 percent when performed by high volume, experienced surgeons.

Focused parathyroidectomy guided by intraoperative PTH monitoring minimizes neck dissection, prevents injury or excision of normally functioning glands, identifies multiple gland disease, and, with few exceptions, assures complete excision of all hyper-secreting glands prior to leaving the operating room. In addition, intraoperative PTH measurements accurately predict postoperative calcium levels.

Intraoperative PTH monitoring takes advantage of the short half-life (three to five minutes) of PTH and utilizes a rapid immuno-assay technique that allows measurements while the patient is still in the operating room. The assay can be completed with a turnaround time of 8 to 20 minutes. Intraoperative rapid PTH assays measure the circulating amount of hormone at the time and from the location where the sample is obtained. Accuracy of intraoperative PTH monitoring is dependent upon the surgeon's knowledge and familiarity with PTH dynamics.