Pictured above: Laboratory team at Humber River Hospital
In 2021, Humber River Hospital (Humber) implemented the use of intraoperative parathyroid hormone (PTH) testing – an analysis used by surgeons to monitor PTH levels during a parathyroidectomy. A parathyroidectomy is the surgical removal of abnormal parathyroid glands as a method to resolve hyperparathyroidism, a disease associated with high blood calcium. Four parathyroid glands are located in the neck, which secrete PTH in response to low calcium. If one or more of these glands create excessive PTH, blood calcium levels become too high and can cause complications if not treated. By performing an intraoperative PTH test during a parathyroidectomy, surgeons are able to determine if they have removed all diseased parathyroid glands, identify the presence of additional diseased parathyroid glands, and remove them before the surgery is completed and the patient returns home.
Intraoperative PTH testing is offered in only a few hospitals in Ontario, including Humber. Key members of the organization were pivotal in bringing this test to Humber, including Dr. Raewyn Seaberg, an otolaryngologist - head and neck surgeon, as well as Dr. Atoosa Rezvanpour, a clinical biochemist and hematology specialist. “The intraoperative PTH analysis is a blood test. It takes advantage of the fact that PTH levels in the blood change very quickly, so the half-life is very short," explains Dr. Seaberg. “Therefore, in real time, we can measure the levels dropping and be sure as surgeons that we have removed all of the diseased parathyroid glands during the course of the operation. Not every parathyroid patient requires this analysis as an adjunct to their surgery, however, there are a subset of patients who benefit."
How Intraoperative PTH Testing Works
Prior to operating on the patient, their PTH levels are noted as a baseline value.
Once the diseased gland is removed during surgery, the PTH levels are tested once again utilizing the intraoperative PTH test.
If all abnormal glands are extracted, results will show a rapid 50% drop in PTH levels of that patient due to the very short half-life of the hormone, which is approximately three to five minutes. With these results, the operating surgeon can be certain that they have fixed the patient's parathyroid disease.
However, if the PTH levels are higher than expected, this indicates that there must be at least a second abnormal gland, which can be found at the time of surgery and consequently removed.
The critical work happens behind-the-scenes in the Laboratory Department at Humber, where the intraoperative PTH test analysis occurs. “Intraoperative PTH tests take approximately 30 minutes to complete from collection to resulting," says Dr. Rezvanpour. “On the day of the surgery, designated laboratory technicians receive the sample, spin and transfer it to an appointed laboratory technologist who will then run the sample. Another technologist will communicate the results with the operating room as soon as testing is completed." PTH levels can be tested repeatedly until all abnormal glands are removed. Without this test, a patient can be sent home without extracting all diseased parathyroid glands, and may have to return.
Development and Implementation at Humber River Hospital
The team at Humber initiated the process of implementing in-house intraoperative PTH tests, as they previously would have to refer patients to other hospitals who offered the test. “In the past, we had patients who would benefit from intraoperative PTH testing, but we didn't have it available. In those cases, we would either need to do a larger operation than necessary and try to find and evaluate all of the glands, or we would need to send these patients to a centre that already has this technology," notes Dr. Seaberg. “Now that we have it available at Humber, we can keep our patients at Humber and offer them this testing in the context of their surgery here."
Developing effective communication methods and a seamless testing system was critical, as intraoperative PTH testing requires multiple measurements of PTH during the surgery. “In order to minimize the testing time, many validations were performed to reduce the pre-analytical and the analytical stages of testing," says Dr. Rezvanpour. “We had to establish procedures on how to transport the samples from the operating room to the laboratory in the shortest time, how to modify the regular maintenance and quality control monitoring, how to process the samples as quickly as possible, and how to communicate the results with the operating room during the surgery."
The intraoperative PTH test is a prime example of the blending of medicine and surgery working together at Humber. “We did the first case in late 2021, and it was such a nice experience working with other parts of the hospital," says Dr. Seaberg. “As surgeons, especially in our subspecialty, we have relationships with pediatricians, endocrinologists, nephrologists, many different specialties, and now we have an excellent close working relationship with the laboratory as well. It is really a collaborative effort to get these tests done for the ultimate benefit of the patients, which is why we're all here."
The intraoperative PTH test at Humber provides eligible patients a solution to their hyperparathyroidism, and assures the operating team that the surgery was successful before the patient leaves the Hospital. This analysis can improve patient outcomes while minimizing risks and the possibility of further surgeries. It aligns with Humber's goal to achieve excellence in patient care by being a high reliability hospital.