Cushing's Disease | How Can a Hormone Imbalance Reshape Your Body?

Cushing's disease is a specific endocrine disorder caused by a benign tumor, known as an adenoma, on the pituitary gland. This gland, located at the base of the brain, is a master controller of the body's hormone systems. The adenoma leads to the overproduction of adrenocorticotropic hormone (ACTH). ACTH travels through the bloodstream to the adrenal glands, situated atop the kidneys, and signals them to produce cortisol. In Cushing's disease, the excessive ACTH stimulation results in chronically elevated levels of cortisol. Cortisol, often called the "stress hormone," is vital for regulating metabolism, immune response, and blood pressure. However, when present in persistently high amounts, it disrupts these normal functions and produces a wide range of physiological and psychological symptoms that define the condition. The core issue is not with the adrenal glands themselves but with the pituitary gland's incorrect signaling.

The most characteristic symptoms of Cushing's disease are metabolic and physical changes driven by high cortisol levels. This includes central obesity, where fat accumulates in the abdomen and torso while the arms and legs remain relatively thin. Cortisol promotes fat redistribution to these central areas. Another hallmark sign is a rounded, full face, often referred to as a "moon face," caused by fat deposits on the sides of the skull. A fatty hump between the shoulders, known as a "buffalo hump," can also develop. Additionally, high cortisol weakens skin proteins, leading to thin, fragile skin that bruises easily and develops wide, purplish stretch marks (striae), particularly on the abdomen.

The terms Cushing's disease and Cushing's syndrome are related but distinct. Cushing's syndrome refers to the general state of having excessive cortisol in the body, regardless of the cause. This can result from external factors, like prolonged use of corticosteroid medications, or from internal issues such as tumors on the adrenal glands. Cushing's disease is the most common endogenous (internal) cause of Cushing's syndrome, specifically identifying the source of the problem as a pituitary adenoma overproducing ACTH. Therefore, all patients with Cushing's disease have Cushing's syndrome, but not everyone with Cushing's syndrome has Cushing's disease.

Diagnosing Cushing's disease involves a multi-step process. The first step is to confirm the presence of hypercortisolism (excess cortisol). This is done through tests such as a 24-hour urinary free cortisol test, a late-night salivary cortisol test, or a low-dose dexamethasone suppression test. If these tests confirm high cortisol levels, the next step is to determine the cause. A blood test to measure ACTH levels is performed. In Cushing's disease, ACTH levels are typically elevated. To pinpoint the tumor's location, imaging studies like an MRI (Magnetic Resonance Imaging) of the pituitary gland are essential.

Hypertension, or high blood pressure, is a frequent and serious complication of Cushing's disease. The excess cortisol affects the cardiovascular system in several ways. Cortisol enhances the effects of other hormones, like adrenaline, that constrict blood vessels, thereby increasing vascular resistance and raising blood pressure. It also directly impacts the kidneys, causing them to retain more sodium and water. This increase in fluid volume within the bloodstream further elevates blood pressure. Over time, this sustained hypertension significantly increases the risk for heart attack, stroke, and kidney disease. Managing blood pressure is a critical part of the overall treatment plan for patients with this condition.