The adrenal glands are small, triangular-shaped organs located on top of each kidney. These glands are part of the endocrine system, a network of glands that produce and release hormones directly into the bloodstream. Adrenal glands play a central role in regulating various bodily functions, including metabolism, blood pressure, and the body’s response to stress. When these glands become “overactive,” it means they produce an excessive amount of hormones, which can lead to a range of health issues.
Adrenal Gland Hormones
The adrenal glands are composed of two main parts: the outer adrenal cortex and the inner adrenal medulla. Each part produces distinct hormones.
The adrenal cortex produces steroid hormones, including cortisol and aldosterone. Cortisol, a glucocorticoid, is often called the “stress hormone” because it helps the body respond to stress by increasing blood sugar, reducing inflammation, and regulating blood pressure. Aldosterone, a mineralocorticoid, is vital for maintaining the body’s salt and water balance. It signals the kidneys to retain sodium and excrete potassium, which in turn helps regulate blood pressure and blood volume.
The adrenal medulla produces catecholamines, primarily adrenaline (epinephrine) and noradrenaline (norepinephrine). These hormones are responsible for the body’s “fight-or-flight” response, rapidly increasing heart rate, blood pressure, and blood flow to muscles and the brain. They also play a role in glucose metabolism, providing quick energy during stressful situations.
When Cortisol Levels Rise Too High
Excessive cortisol production leads to a condition known as Cushing’s Syndrome. This syndrome can arise from several different sources. The most common cause is the prolonged use of high-dose corticosteroid medications, such as prednisone, which mimic natural cortisol. This external intake leads to symptoms similar to those caused by internal overproduction.
Tumors in the pituitary gland, located at the base of the brain, can cause this condition. These usually benign tumors, called pituitary adenomas, produce excessive adrenocorticotropic hormone (ACTH), which overstimulates the adrenal glands to produce too much cortisol. This specific form of Cushing’s Syndrome, caused by a pituitary tumor, is known as Cushing’s Disease and accounts for a significant majority of endogenous cases.
The problem can also originate directly within the adrenal glands. A benign or, less commonly, cancerous tumor on one or both adrenal glands can autonomously produce too much cortisol, independent of ACTH signals from the pituitary gland.
Some tumors located outside the pituitary or adrenal glands, such as those in the lung, pancreas, or thymus, can also produce ACTH. This “ectopic” ACTH then stimulates the adrenal glands, leading to high cortisol levels and Cushing’s Syndrome.
When Aldosterone Levels Rise Too High
An excess of aldosterone, called primary aldosteronism or Conn’s Syndrome, affects blood pressure and electrolyte balance. This overproduction causes the kidneys to retain too much sodium and water while excreting potassium, leading to high blood pressure and potentially low potassium levels. The most frequent cause is a benign tumor, an adrenal adenoma, on one of the adrenal glands. This adenoma produces aldosterone independently.
Another cause of elevated aldosterone is bilateral adrenal hyperplasia, where both adrenal glands become enlarged and overactive. This leads to an overproduction of aldosterone from both glands, contributing to high blood pressure that can be resistant to standard treatments. While adrenal adenomas account for about 30-40% of primary aldosteronism cases, bilateral adrenal hyperplasia is responsible for approximately 60-70% of cases.
When Catecholamine Levels Rise Too High
Excessive production of adrenaline and noradrenaline, known as catecholamines, is caused by a rare tumor called a pheochromocytoma. This tumor usually develops in the adrenal medulla. Pheochromocytomas cause the adrenal glands to release high amounts of these “fight-or-flight” hormones.
The cause of many pheochromocytomas remains unknown, with over half of cases occurring sporadically. About 25-35% of these tumors are linked to inherited genetic conditions. These genetic disorders, such as Multiple Endocrine Neoplasia type 2 (MEN2), Von Hippel-Lindau (VHL) disease, and Neurofibromatosis type 1 (NF1), can predispose individuals to pheochromocytomas. The overproduction of these hormones can lead to symptoms such as sudden, severe spikes in blood pressure, rapid heartbeat, headaches, and excessive sweating.