Parathyroid gland transplant foils permanent hypoparathyroidism
Risk of permanent condition drops as number of glands transplanted increases
Autotransplanting parathyroid glands to a muscle of the neck after surgery to remove the thyroid gland is tied to a higher risk of transient hypoparathyroidism, but progresses to permanent hypoparathyroidism less often, a study in China suggests.
The risk of permanent hypoparathyroidism, that is, that which lasts more than six months, alsoo decreased as the number of autotransplanted parathyroid glands increased. According to the researchers, “autotransplantation is recommended for parathyroid glands that are [deprived of blood supply] or challenging to preserve in their original location.”
The study, “Selective parathyroid autotransplantation prevent permanent hypoparathyroidism after total thyroidectomy with central neck dissection,” was published in Frontiers in Surgery.
Hypoparathyroidism is defined by reduced levels of parathyroid hormone, or PTH, which helps regulate calcium and phosphorus in the body. When PTH levels are too low, calcium levels become abnormally low and phosphorus levels rise.
Permanent hypoparathyroidism is a long-term complication that can occur after surgery to remove the thyroid gland, as the four parathyroid glands are located close to the thyroid in the neck and may be damaged during surgery. Studies show conflicting results about whether auto-transplanting at least one parathyroid gland may minimize the risk of permanent hypoparathyroidism.
Effect of autotransplanting parathyroid glands
Researchers in China retrospectively analyzed 1,153 people with thyroid cancer who had surgery to remove their thyroid plus central neck dissection to remove lymph nodes, organs of the lymphatic and immune systems that may be affected by cancer.
The participants were a mean age of 44.9 and most were women (78.4%). A total of 501 patients underwent autotransplant of at least one parathyroid gland into the sternocleidomastoid muscle of the neck, while 652 didn’t receive the autotransplant.
In more than half the participants in both groups, the cancer had spread to the neck lymph nodes. Dissection was most commonly done on one side (61.8%) of the neck and involved both sides in 38.2% of the patients. Bilateral surgery was more common in autotransplanted patients (57.9% vs. 23.2%), who were also more likely to have more advanced cancer.
The participants who had an autotransplant had a significantly lower rate of parathyroid glands inadvertently removed during the surgery (20.6% vs. 32.4%), were more likely to experience transient hypoparathyroidism (67.1% vs. 49.8%), and less likely to have it permanently (1.2% vs. 4.4%) over those who didn’t have autotransplant.
A total of 651 glands were autotransplanted, varying from one (31%), two (11.8%), or three (0.6%) per patient. In most cases, the autotransplanted glands were initially removed due to devascularization, or loss of blood flow (57.9%), while 42.1% of them were accidentally removed during the surgery.
As the number of autotransplanted glands increased, the prevalence of permanent hypoparathyroidism decreased, from 4.4% in non-transplanted patients to 0% for those receiving three glands. In contrast, transient hypoparathyroidism increased with the number of autotransplanted glands, from 49.8% in non-transplanted patients to 85.7% in those receiving three glands.
As for the group in whom the parathyroid glands weren’t accidentally removed, which included 398 patients who were autotransplanted and 441 not transplanted, transient hypoparathyroidism was significantly higher in the autotransplanted patients (66.8% vs. 47.2%), but permanent hypoparathyroidism was lower (0.3% vs. 3.2%).
Women were 48.7% more likely to have transient hypoparathyroidism. Bilateral (versus unilateral) and having at least one autotransplanted parathyroid gland also were associated with a higher risk of transient hypoparathyroidism. The risk of progressing to permanent hypoparathyroidism was 2.8 times higher in those whose parathyroid glands were accidentally removed. Parathyroid autotransplantation decreased that risk by almost 77%.
“Undoubtedly, parathyroid autotransplantation stands as an efficacious method to restore parathyroid gland function after devascularization or identification in surgical specimens,” the researchers wrote. “Our study reveals that parathyroid autotransplantation heightens the occurrence of transient hypoparathyroidism, but substantially diminishes the risk of permanent hypoparathyroidism.”
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