Excess Thyroid Hormones Can Be Rare Complication After Surgery

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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Thyrotoxicosis, or abnormally high levels of thyroid hormones in the body, is a rare complication that can occur in people with Cushing’s disease who undergo tumor-removal surgery, a new report highlights.

The study, “Management of thyrotoxicosis occurring after surgery for Cushing’s disease: a case series,” was published in the journal Gland Surgery.

Cushing’s disease is caused by a tumor in the brain’s pituitary gland, which leads to abnormally high levels of the stress hormone cortisol in the body, a condition known as hypercortisolism. Surgical removal of the disease-causing tumor is the standard treatment for Cushing’s disease.

High cortisol levels in Cushing’s disease — and the shift to lower levels after surgery — can cause a variety of changes in body tissues, through mechanisms that are still not fully understood. One organ that can be affected is the thyroid gland.

The thyroid is a butterfly-shaped gland found at the base of the throat. It secretes several hormones, called thyroid hormones, that help regulate metabolism and other bodily processes. Thyrotoxicosis is a condition that occurs when the levels of these hormones rise too high; common symptoms of thyrotoxicosis include weight loss, heat sensitivity, and heart palpitations.

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In the new report, researchers at Peking Union Medical College in China screened the medical records of 732 Cushing’s patients who underwent surgery at their institution between 2010 and 2017.

Of these, 14 (1.9%) developed thyrotoxicosis after having surgery. Among these 14 patients, who were all female, the age at diagnosis ranged from 16 to 80 years, and the median disease duration was three years. These patients were in remission from Cushing’s, that is, they no longer had high cortisol levels, following surgery.

None of the 168 analyzed patients who were not in remission following surgery developed thyrotoxicosis. This suggests that the development of this rare post-surgery complication is likely biologically tied to the dip in cortisol levels following surgery, according to the researchers.

One of the 14 patients had severe symptoms of thyrotoxicosis, including weight loss and heart palpitations. She required persistent treatment to manage the condition.

Six others had moderate symptoms and were successfully treated with a limited course of beta-blockers, a type of medication routinely used to treat thyrotoxicosis. The other seven patients had mild symptoms and did not require specific treatment for thyrotoxicosis.

Thyrotoxicosis was diagnosed a median of 3.5 months after surgery. Researchers noted that it tended to develop during the period of adrenal insufficiency in the months shortly after surgery, when the body is producing lower-than-normal amounts of cortisol as it is still adjusting to the lack of the disease-causing tumor.

“We have shown that thyrotoxicosis is a rare complication during the recovery period following [surgery for Cushing’s disease] and that it occurs only after the resolution of hypercortisolism, and particularly in the context of adrenal insufficiency during the 4 months following [disease] remission,” the researchers wrote.

“It is important to promote awareness of this potential complication among physicians,” they wrote, adding that “the most appropriate means of managing patients should be determined on the basis of the clinical setting and the clinical manifestation of the thyrotoxicosis.”