Trial Assesses Benefits of New Parathyroid Auto-Transplantation Site for Hypoparathyroidism

A team of Chinese researchers is conducting a clinical trial to test a new parathyroid auto-transplantation site for patients with hypoparathyroidism.

The study protocol was published in an article, “Parathyroid autotransplantation at a novel site for better evaluation of the grafted gland function: study protocol for a prospective, randomized controlled trial,” in the journal Trials.

Hypoparathyroidism is a rare disorder caused by low levels of the parathyroid hormone (PTH). It is one of the most common complications associated with thyroidectomy — a surgical procedure to remove the entire thyroid gland that can also damage the parathyroid glands, which are responsible for the production of PTH.

The parathyroid and thyroid glands are located at the front of the neck, and are responsible for the production and secretion of hormones important for growth, bone health, and body metabolism.

One therapeutic method for patients whose parathyroid glands have been damaged and/or unintentionally removed during surgery is parathyroid auto-transplantation (PA). This technique removes a portion of the patient’s parathyroid gland and places it into the muscle of the neck or forearm, in an attempt to normalize the production of PTH.

Preliminary findings from the same team in China have shown that patients who received PA after undergoing a thyroidectomy in the forearm had higher levels of PTH in their serum when the transplantation site was closer to the antecubital vein (the superficial vein from the forearm that is normally used to draw blood), rather than farther away (the traditional PA site).

The subsequent prospective, randomized controlled trial (NCT02906748), sponsored by Tongji Hospital in China, intends to confirm whether the new PA site is more useful in monitoring PTH levels, and, at the same time, whether it provides better clinical outcomes compared to the traditional PA site.

A total of 280 patients, who underwent thyroidectomy and whose parathyroid glands were sufficiently healthy to be transplanted, were divided into two groups: 140 received PA at the traditional site (group A, which was the control group), and the remaining 140 received PA at the new site closer to the antecubital veins (group B). PTH and calcium serum levels were measured in both forearms for a followup period of one year.

The study’s objective was to evaluate the survival and activity of grafted parathyroid glands by measuring the ratio of PTH between the grafted and non-grafted forearms (the ratio should be higher than 1.5 for a successful PA) at one month, and at three and six months after the transplant.

Researchers also assessed hypoparathyroidism, which is defined as PTH serum levels from the non-grafted forearm that is lower than 15 pg/ml (normal range is 15 to 65 pg/ml).

“Our results. . . should provide a more accurate method to evaluate the function of transplanted parathyroid glands by comparing PTH concentrations in both the grafted and non-grafted forearms following PA at novel sites. A better PTH measurement is helpful not only for the management of postoperative patients, but also for further identification of factors affecting PA success,” the researchers wrote.

The study, which started in April 2016, was recruiting at the time of manuscript submission in May 2018, and was expected to be completed in December 2018.