Post-surgical hypoparathyroidism is a common temporary complication in patients who undergo thyroid removal surgery, occurring more frequently in patients with inflammation of the thyroid, known as thyroiditis, a study has found.
However, permanent hypoparathyroidism, lasting more than six months after surgery, affects a much smaller proportion (2-3 percent) of patients and is as likely in thyroiditis as in nonthyroiditis cases, according to the report.
The study, “The Impact of Thyroiditis on Morbidity and Safety in Patients Undergoing Total Thyroidectomy,” was published in the Indian Journal of Endocrinology and Metabolism.
Patients with thyroiditis are normally not referred for a thyroidectomy — the surgical removal of all or part of the thyroid — because the inflammatory process associated with thyroiditis may increase the risk of injury to the surrounding tissues, such as the parathyroid glands. This, in turn, may increase the risk of hypoparathyroidism.
The procedure may also damage the recurrent laryngeal nerve, the nerve that supplies most muscles of the larynx, including those controlling the vocal cords. Injury to this nerve may result in its paralysis, completely blocking the vocal cords.
However, in specific situations, these patients may be recommended for surgery, including when physicians suspect a malignant goiter, an enlargement of the thyroid gland caused by a tumor, or persistent symptoms not controlled by standard medication.
In light of the risks associated with a thyroidectomy, researchers compared the incidence of postoperative complications, including hypoparathyroidism, in patients with thyroid gland disorders, mostly goiter, undergoing a total thyroidectomy.
The study included 724 patients — 272 cases of thyroiditis and 452 of nonthyroiditis. Patients were recruited from a tertiary care center at the Madras Medical College in south India, a region where patients with thyroiditis are particularly frequent.
Patients were monitored for temporary postoperative complications, defined as those lasting less than six months, and permanent complications, lasting longer than that.
Many temporary complications occurred much more frequently in patients who had thyroiditis before surgery than in those who did not, including low levels of calcium in the blood (39.7% vs. 24.77%), hypoparathyroidism (39.7% vs. 24.77%), and vocal cord paralysis (9.55% vs. 7.52%).
A group analysis, separating thyroiditis patients with a goiter associated with nodules from those with Hashimoto’s thyroiditis — an autoimmune disease in which a person’s immune system mistakenly attacks the thyroid gland — showed that the incidence of temporary hypoparathyroidism was significantly higher in those with Hashimoto’s thyroiditis.
On a six-month follow-up, a small proportion of patients still had hypoparathyroidism or paralysis of the vocal cords. But their incidence was no longer significantly different between thyroiditis and nonthyroiditis patients (3.3% vs. 2.21% and 3.3% vs. 1.76%, respectively).
“The incidences of transient complications are higher in patients with thyroiditis,” the researchers said, although permanent complications are comparable between them.
Given the elevated risk of complications, including temporary hypoparathyroidism, following thyroidectomy, “careful analysis of surgical indications will avoid unnecessary surgery in thyroiditis cases,” they concluded.