Cushing’s Syndrome is a condition caused by prolonged exposure to excessive levels of cortisol, a hormone naturally produced by the body. This imbalance leads to a range of physical and psychological changes. This article provides an overview of Cushing’s Syndrome, covering its causes, symptoms, and management.
What is Cushing’s Syndrome?
Cushing’s Syndrome (ICD-10: E24) describes a state where the body experiences prolonged exposure to high levels of cortisol. Cortisol, often called the “stress hormone,” is a steroid hormone produced by the adrenal glands. It plays a role in nearly every organ and tissue system, regulating the body’s stress response, metabolism, immune function, blood pressure, and sleep-wake cycle. When cortisol levels are consistently elevated, these normal bodily processes are disrupted, leading to the characteristic signs and symptoms.
Recognizing the Signs
A common indicator is weight gain, particularly around the midsection, face, and upper back, often resulting in a rounded face, sometimes called a “moon face,” and a fatty lump between the shoulders, known as a “buffalo hump.” Individuals may also experience thinning of the arms and legs, a contrast to the central obesity.
Skin changes are also frequently observed, including thin, fragile skin that bruises easily, and wide, purple or reddish stretch marks (striae) on the abdomen, thighs, breasts, and arms. This occurs because high cortisol levels can break down skin proteins and weaken blood vessels.
Other physical symptoms often include muscle weakness, especially in the hips and shoulders, fatigue, high blood pressure, and elevated blood sugar levels.
Cushing’s Syndrome can also impact mental and emotional health. Patients may experience mood changes such as depression, anxiety, and increased irritability. Difficulty with concentration, memory problems, and sleeplessness are also reported.
In women, hormonal imbalances can lead to irregular or absent menstrual periods and excessive hair growth on the face and body. Men may experience decreased fertility and erectile dysfunction.
Understanding the Causes
Cushing’s Syndrome arises from an excess of cortisol, which can originate from external sources or from the body’s own overproduction.
The most common cause is exogenous Cushing’s Syndrome, also known as iatrogenic Cushing’s. This form occurs when individuals take high doses of glucocorticoid medications, such as prednisone, over an extended period. These medications are often prescribed to manage inflammatory conditions like asthma, rheumatoid arthritis, or lupus, or to suppress the immune system after organ transplantation.
In contrast, endogenous Cushing’s Syndrome results from the body’s internal overproduction of cortisol, often due to various types of tumors. The most frequent endogenous cause is Cushing’s Disease (ICD-10: E24.0), accounting for about 70-80% of spontaneous cases.
This specific type is caused by a benign tumor in the pituitary gland, which produces excessive adrenocorticotropic hormone (ACTH). ACTH then stimulates the adrenal glands to produce too much cortisol.
Another cause of endogenous Cushing’s Syndrome involves tumors directly on the adrenal glands (ICD-10: E24.1). These adrenal tumors, typically benign, independently produce excessive cortisol, leading to high levels in the body.
Less commonly, Cushing’s Syndrome can result from ectopic ACTH production (ICD-10: E24.3). In these cases, a tumor located outside the pituitary gland, often in the lungs, pancreas, thyroid, or thymus, produces ACTH, thereby stimulating the adrenal glands to overproduce cortisol.
Diagnosis and Management
Diagnosing Cushing’s Syndrome involves a series of tests to confirm excess cortisol and identify its source.
Initial screening tests typically include a 24-hour urinary free cortisol test, measuring cortisol excreted in urine over a full day. A late-night salivary cortisol test checks cortisol levels when they should be at their lowest.
A low-dose dexamethasone suppression test may also be used. Here, a small dose of dexamethasone (a synthetic steroid) is given, and cortisol levels are measured to see if they suppress as expected.
Once elevated cortisol is confirmed, further tests determine the underlying cause. An ACTH blood test helps differentiate between ACTH-dependent and ACTH-independent causes. High-dose dexamethasone suppression tests can help pinpoint if the problem originates in the pituitary gland.
Imaging studies, such as an MRI of the pituitary gland or a CT scan of the adrenal glands, are often performed to locate tumors. In complex cases, bilateral inferior petrosal sinus sampling (BIPSS) may be utilized to accurately determine if the pituitary is the source of excess ACTH.
Management of Cushing’s Syndrome depends on its cause. For exogenous Cushing’s, treatment involves the gradual reduction of steroid medication under medical supervision.
For endogenous causes, surgical removal of the tumor is often the primary treatment. This includes transsphenoidal surgery for pituitary tumors, or removal of adrenal or ectopic tumors. If surgery is not possible or unsuccessful, other options are considered.
Radiation therapy may be used for pituitary tumors. Medications are also available to help control cortisol production, such as ketoconazole, mifepristone, pasireotide, osilodrostat, and metyrapone, which work by blocking cortisol synthesis or its effects.
Because Cushing’s Syndrome can significantly impact health, a multidisciplinary approach involving endocrinologists, surgeons, and other specialists is important for effective diagnosis and management.