Minimally Invasive Parathyroidectomy

New Technology Ensures Safe, Effective Surgery

Thanks to new technology, minimally invasive parathyroidectomy is now a desirable treatment option for primary hyperparathyroidism, says UAB otolaryngologist Glenn E. Peters, MD. “In the past, standard surgical treatment involved bilateral exploration of the neck to identify and resect enlarged hypersecreting parathyroid gland(s). In 85% of patients this meant major surgery to remove only one gland,” he discloses.

According to Peters, the new treatment options are possible because of the development of two tests — the technetium-99m sestamibi scan and the rapid intraoperative, intact parathyroid hormone (iPTH) assay. “Using these advances, we now can localize adenomas preoperatively, remove them with a much smaller incision, and confirm successful excision before the patient leaves the operating room,” he underscores.

Sestamibi Scan
“Prior to surgery,” Peters describes, “the patient is injected with the radiolabeled protein technetium-99m sestamibi, which is rapidly taken up and then slowly cleared from the thyroid and normal parathyroid glands. However, it persists in overactive parathyroid tissue.” Approximately 2 hours later, the patient undergoes a nuclear scan that produces a three-dimensional image, which can be taken to the operating room for visual reference. “The scan has a sensitivity of approximately 80%, so, in most cases, enlarged glands are clearly visible on the image,” says Peters.

The scan also can indicate a gland’s precise location, which helps predict the technical difficulty and the patient’s candidacy for a minimally invasive procedure. “Instead of traditional bilateral surgery, we can now go directly to the gland using only a 2-cm incision,” he notes. However, if more than one of the parathyroid glands are equally radioactive, or none of the glands is visualized, the patient undergoes traditional parathyroidectomy using the bilateral approach.

Additionally, the sestamibi scan can be utilized intraoperatively. In minimally invasive radio-guided parathyroidectomy (MIRP), a miniature gamma probe is periodically inserted to locate areas of increased uptake and direct dissection. “MIRP is used primarily on patients with scar tissue due to previous neck surgery or when the gland is in an abnormal location,” Peters explains.

Rapid iPTH Assay
Once the adenoma is removed, the patient’s parathyroid hormone level drops significantly. As a result, successful excision can be confirmed using the rapid iPTH assay. “Ten to 20 minutes after removing the gland, we draw a blood sample and check the iPTH level. If it drops by 50% to 60%, then the operation is complete,” he says.

With a success rate of 97%, minimally invasive parathyroidectomy eliminates the risk of hypocalcemia by preventing the injury or removal of normal glands. The procedure also reduces the risk of damage to the recurrent laryngeal nerves by limiting surgery to one side of the neck. “With the sestamibi scan and the rapid iPTH assay, patients can now have an outpatient procedure that produces fewer complications and excellent results,” concludes Peters.

For more information:
Dr. Glenn E. Peters
1-800-UAB-MIST
mist@uabmc.edu