Overview of the adrenal glands
The adrenal glands are a small pair of triangle-shaped yellow organs that rest on top of the kidneys. They are made of two layers: the outer cortex, and the inner medulla.
The outer layer of the adrenal gland (cortex)
The outer cortex makes hormones essential to life, aldosterone and cortisol, and also makes sex steroids. All hormones made by the cortex arise from cholesterol.
• Aldosterone helps to maintain water/salt balance, blood pressure, and potassium levels.
• Cortisol regulates metabolism, response to stress, the immune system, and decreases inflammation in the body.
• Sex steroids (androgen/DHEA, estrogen, and progesterone) are also secreted by the cortex in small amounts.
The inner layer of the adrenal gland (medulla)
The medulla (inner layer of the adrenal gland) makes adrenaline, noradrenaline (also called epinephrine and norepinephrine) which are critical in the “fight or flight” response. The hormones are released when one is feeling stress. Release of adrenaline causes an increase in heart rate, increased blood flow to the brain and muscles, and release of sugar from the liver into the blood stream. Noradrenaline helps to raise blood pressure by tightening blood vessels.
What diseases can arise within the adrenal glands?
Sometimes, the cortex can fail to produce enough cortisol and aldosterone, resulting in underactive adrenal glands. Extreme weakness, fatigue, and shock can result if untreated. This condition is called Addison Disease and is rare.
More commonly, a growth can arise within the adrenal gland. Usually, these growths are benign (non-cancerous) and non-functioning (not making too much hormones). At times, they can make too much hormone (adrenaline, cortisol, or aldosterone), or be concerning for cancer; in that case surgery would be recommended. See the other links in this section (adrenal disorders) to learn more.
- Genetic Mutation
- A problem in another gland, such as the pituitary, which helps to regulate the adrenal glands
- Certain Medicines
Interesting adrenal facts
• The first person credited to accurately describe and illustrate the adrenal glands was Bartholomeus Eustachius (1520-1574), an anatomy professor in Rome.
• Roger Bannister (1st person to run a sub 4 min mile) and John F Kennedy had Addison’s disease.
• Sister Mary Joachim, was one of the first patients to undergo successful adrenalectomy for pheochromocytoma that was not diagnosed preoperatively, in 1926. Her blood pressure was maintained after surgery with coffee enemas (not recommended today!).
• President Eisenhower developed severe heart disease during his lifetime; on autopsy, he was found to have an undiagnosed pheochromocytoma.