What is Cushing's syndrome and what causes it?

Cushing's syndrome is a hormonal disorder that occurs as a result of the body being exposed to high levels of the hormone cortisol for a long period of time [1]. Cortisol, known as the "stress hormone," plays a vital role in the body; it helps regulate blood pressure, control blood sugar levels, reduce inflammation, and convert food into the energy the body needs to function [1]. When the adrenal glands, located above the kidneys, overproduce this hormone, side effects begin to appear in various body systems [1].

Why does Cushing's syndrome occur?

The causes of Cushing's syndrome are primarily divided into two types based on the source of excess cortisol. The most common type is related to external factors, while the other is related to dysfunction within the body [1].

• Exogenous Cushing's syndrome: This condition results from long-term use of high doses of glucocorticoid medications that mimic cortisol [1]. These medications are prescribed to treat various medical conditions such as asthma, lupus, and rheumatoid arthritis, and are also used as localized injections to relieve joint pain [1].
• Endogenous Cushing's syndrome: In this case, the body produces an excess of cortisol internally as a result of specific tumors [1]. The most frequent cause (accounting for 8 out of 10 non-medication-related cases) is a benign tumor in the pituitary gland that secretes ACTH, a hormone that stimulates the adrenal gland to produce excess cortisol [1]. Tumors located outside the pituitary gland, such as those in the lung, pancreas, or thyroid, can also secrete this same stimulating hormone [1]. In less common cases, a tumor may arise in the adrenal gland itself, leading to direct cortisol secretion [1].

Cushing's symptoms and warning signs

The severity and variety of symptoms differ based on cortisol levels and duration, but noticeable physical signs may include weight gain and fat accumulation in specific areas, such as a rounded face, fat around the base of the neck, and a fatty hump between the shoulders, alongside thinning limbs and muscle weakness [1]. Wide purple stretch marks may also appear on the abdomen, chest, or thighs, in addition to easy bruising [1]. For more details on how this affects the body, see our article on Cushing's syndrome: Cortisol increase and body changes (Arabic).

Diagnosis and next steps

Due to the similarity of symptoms with other conditions such as obesity or polycystic ovary syndrome, doctors rely on precise examinations including blood, saliva, and urine tests to measure cortisol throughout the day [1]. The dexamethasone suppression test is often used to assess the body's normal response; it is expected that cortisol levels will drop after taking a specific dose of dexamethasone, and a failure to drop is a strong indicator of the syndrome [1]. If you suspect you have this condition, do not attempt to self-diagnose or stop taking any steroid medications you are on without consulting your doctor, as sudden cessation can lead to serious complications [3]. Contact an endocrinologist to perform the necessary tests, as treatment depends entirely on identifying the underlying cause, whether it is tumor-related or medication-related [1].

Medical references

• Cushing's Syndrome
• ACTH blood test