Cushing’s by Different Causes May Have Similar Effects on Metabolism

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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Cushing’s syndrome triggered by different causes can have similar effects on a person’s metabolism, or the set of chemical changes that take place in the body, a study suggests.

The study, “Metabolic profile differences in ACTH-dependent and ACTH-independent Cushing syndrome,” was published in the journal Chronic Diseases and Translational Medicine.

Cushing’s syndrome occurs when the adrenal glands, which sit atop the kidneys, produce too much cortisol.

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Too much cortisol can be caused by the brain’s pituitary gland making too much adrenocorticotropic hormone (ACTH), a hormone that stimulates the adrenal glands to produce cortisol. This occurs in about 70%–80% of Cushing’s cases and is generally secondary to a pituitary adenoma (a benign tumor).

About 20%–30% of cases can occur in a way that is independent of ACTH and is usually secondary to an adrenal tumor or an enlarged adrenal gland.

Studies have shown that people with ACTH-dependent Cushing’s syndrome are younger, have more skin problems, and are more likely to develop hirsutism (excessive hair growth in the face and other body parts) than those with ACTH-independent Cushing’s syndrome.

“Despite the findings of these studies, differences in the metabolic factors … remain unclear,” the researchers wrote.

To shed light on this matter, they reviewed the medical records of 114 patients who received a diagnosis of Cushing’s syndrome between October 2009 and October 2019; 64 had an adrenal gland disorder and 50 had an ACTH-producing pituitary adenoma.

More women than men had Cushing’s syndrome in the study: women made up 88% of the ACTH-dependent Cushing’s group, and 92% of those with ACTH-independent Cushing’s.

People with ACTH-dependent Cushing’s syndrome received a diagnosis at a younger age (35.4) than those in the ACTH-independent group (39.65), but the difference was not statistically significant. They also had higher levels of cortisol and ACTH at various times of the day.

No significant differences were found in weight, body mass index (a ratio of a person’s weight to height), and blood pressure between the two groups.

The researchers also found no differences between the two groups in blood levels of cholesterol and fats called triglycerides. The amount of uric acid — a waste product found in blood that has been linked to high blood pressure — was also not different.

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Although the amount of sugar in the blood did not differ between the two groups, diabetes — a metabolic disease marked by high levels of blood sugar — was more common among people with ACTH-dependent Cushing’s syndrome than among those with ACTH-independent disease.

However, the proportion of people with other metabolic disturbances, such as hypertension (high blood pressure) or dyslipidemia (abnormal levels of cholesterol and fats in the blood), did not differ between the two groups.

“Metabolic disturbance has been the most common complication for patients with Cushing’s syndrome,” the researchers wrote.

Although ACTH-dependent and ACTH-independent Cushing’s syndrome have different causes, they appear to have “similar metabolic characteristics,” they said, adding that “further experimental studies are needed to evaluate the metabolic effects of ACTH and to validate the present study’s findings.”