Your adrenal glands produce more than 50 different hormones, but the major ones fall into five categories: cortisol, aldosterone, adrenaline, noradrenaline, and androgens like DHEA. Each adrenal gland sits on top of a kidney and has two distinct parts, the outer cortex and the inner medulla, which function almost like separate organs. The cortex handles long-term metabolic regulation, while the medulla drives your rapid stress response.
How the Adrenal Gland Is Structured
The outer cortex makes up about 80% of the gland and is divided into three layers, each producing a different class of hormone. The outermost layer (zona glomerulosa) produces aldosterone. The middle layer (zona fasciculata) produces cortisol. The innermost layer (zona reticularis) produces androgens. These three layers operate somewhat independently, each responding to different signals from the brain and bloodstream.
The inner medulla is essentially a modified part of your nervous system. It releases adrenaline and noradrenaline directly into the blood in response to signals from the sympathetic nervous system, the branch that controls your fight-or-flight response.
Cortisol: The Body’s Metabolic Manager
Cortisol is the most well-known adrenal hormone and arguably the most far-reaching. It regulates how your body uses glucose for energy by triggering your pancreas to decrease insulin and increase glucagon, effectively raising blood sugar when you need it. It also prompts your liver to release stored glucose, providing fast fuel during stressful moments. Cortisol acts on fat tissue, muscle, and liver simultaneously to coordinate energy availability across the whole body.
Beyond metabolism, cortisol shapes your immune response. In short bursts, it limits inflammation and can actually boost immunity. But when cortisol stays elevated for long periods, the body adapts to it, which can lead to increased inflammation and a weakened immune system. Cortisol also influences blood pressure, though the exact mechanism in humans isn’t fully understood. Chronically high levels raise blood pressure, while abnormally low levels can cause it to drop.
Cortisol follows a predictable daily rhythm. Levels peak in the early morning, with blood concentrations typically reaching 10 to 20 micrograms per deciliter between 6 and 8 a.m. By 4 p.m., levels drop to roughly 3 to 10 mcg/dL, and they hit their lowest point around midnight. This cycle is why blood tests for cortisol are usually drawn first thing in the morning.
How Cortisol Production Is Controlled
Your brain regulates cortisol through a chain reaction called the HPA axis. When you encounter stress, your hypothalamus releases a signaling hormone that tells the pituitary gland to release ACTH. ACTH travels through the blood to your adrenal cortex, which responds by producing cortisol. Once cortisol levels rise high enough, the hypothalamus detects this and stops sending the initial signal, shutting the loop down. This negative feedback system is meant to keep cortisol tightly regulated, though chronic stress can disrupt it.
Aldosterone: Blood Pressure and Electrolyte Balance
Aldosterone is the only mineralocorticoid your adrenal glands produce, and its primary job is managing sodium and potassium levels. It acts on the kidneys, specifically the later segments of the filtering tubes, where it increases the number of sodium channels in cell membranes. More channels mean more sodium gets pulled back into the blood rather than lost in urine. Water follows sodium, so this process directly raises blood volume and blood pressure.
On the flip side, aldosterone promotes potassium excretion through urine. When you eat a high-potassium diet, aldosterone levels rise to help your kidneys clear the excess. This sodium-potassium balancing act is why conditions that produce too much or too little aldosterone cause such dramatic shifts in blood pressure and electrolyte levels.
Aldosterone operates through a different control system than cortisol. When blood pressure or blood volume drops, your kidneys release an enzyme that sets off a cascade ending with a molecule called angiotensin II, which directly triggers your adrenal glands to release aldosterone. Rising potassium levels in the blood also stimulate aldosterone release independently. This means aldosterone responds to what’s happening in your blood and kidneys rather than to signals from the brain.
Adrenaline and Noradrenaline: The Acute Stress Hormones
The adrenal medulla produces two closely related hormones: adrenaline (epinephrine) and noradrenaline (norepinephrine). Unlike cortisol, which ramps up over minutes to hours, these hormones hit the bloodstream within seconds.
Adrenaline is released in response to low blood sugar or physical exercise, in addition to acute stress. It increases heart rate, opens airways, and redirects blood flow toward muscles. Noradrenaline raises blood sugar, narrows blood vessels, and increases blood pressure. Together, they prepare the body to respond to immediate physical demands. Once the triggering event passes, these hormones are broken down quickly and their effects fade within minutes.
DHEA and Other Adrenal Androgens
The innermost layer of the adrenal cortex produces androgens, the most prominent being DHEA (dehydroepiandrosterone). These are not potent sex hormones on their own. Instead, DHEA serves as a precursor that the body converts into testosterone and estrogen in other tissues. This makes the adrenal glands a meaningful source of sex hormones, particularly in women, where the adrenals contribute a larger proportion of total androgen production than in men. DHEA production peaks in your mid-20s and declines steadily with age.
What Happens When Adrenal Hormones Are Out of Balance
When the adrenal glands produce too little cortisol and aldosterone, the result is adrenal insufficiency. The most common symptoms are chronic fatigue, muscle weakness, appetite loss, and weight loss. Low aldosterone specifically leads to salt cravings, low blood pressure that worsens when standing (sometimes causing dizziness or fainting), and disrupted potassium levels. People with Addison’s disease, the autoimmune form of adrenal insufficiency, often develop darkened skin on scars, skin folds, elbows, knees, and the lining of the mouth.
Other symptoms of adrenal insufficiency can include nausea, vomiting, diarrhea, low blood sugar, irritability, depression, and irregular menstrual periods. A morning blood cortisol level below 3 mcg/dL, combined with consistent symptoms, generally points to adrenal insufficiency without the need for further testing. Levels above 13 to 18 mcg/dL typically rule it out.
Too much cortisol over a prolonged period causes Cushing’s syndrome, which produces a very different picture: weight gain concentrated in the face and midsection, thinning skin that bruises easily, high blood sugar, high blood pressure, and muscle weakness. The contrast between these two conditions illustrates just how central adrenal hormones are to daily functioning, affecting everything from energy levels and blood pressure to skin appearance and mood.