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What is Cushing’s Syndrome?

Cushing’s syndrome (CS) is a rare problem caused when the adrenal gland(s) makes too much of a hormone called cortisol. CS is most often due to a tumor or mass found in the pituitary gland, but can also be caused by tumors in the adrenal glands themselves.

People with Cushing's syndrome may see their face get round ("moon face"), they gain weight in unusual ways, bruise easily or feel weak, tired and sad. Women and men may also notice fertility and other problems. CS is most often found in adults between the ages of 20 and 50.

Anatomy of the Adrenal Glands
Anatomy of the Adrenal Glands
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What Happens Under Normal Conditions?

The adrenal glands are found above each kidney. They are triangle-shaped, and measure about half an inch in height and 3 inches in length. Each adrenal gland has 2 layers.

  • The adrenal medulla (inner part) makes epinephrine (also called adrenaline).
  • The adrenal cortex (outer part) makes steroid hormones (such as cortisone and aldosterone).

The adrenal glands control many processes in the body. Their job is to keep the body in balance by making various hormones that are critical for maintaining good health.

Adrenal glands

These hormones do many important things. For example, they help regulate fluid and salt levels in the body that affect blood volume and blood pressure. They also help the body react to stress and change. They cause a faster heart rate and boost other systems that help you to react quickly with a burst of energy when needed. Problems in the cortex or the medulla, then, can result in high blood pressure.

Cortisol levels are controlled by the pituitary gland, which is found at the base of the brain. The hypothalamus of the brain makes the corticotropin-releasing hormone (CRH). CRH tells the pituitary gland to release signals that control how much cortisol the adrenal glands make. The pituitary gland signal is called corticotropin or adrenocorticotropic hormone (ACTH).

The hypothalamus sends CRH to the pituitary, which responds by secreting ACTH.  ACTH then causes the adrenals to release cortisol into the bloodstream.
The hypothalamus sends CRH to the pituitary, which responds by secreting ACTH. ACTH then causes the adrenals to release cortisol into the bloodstream.
Image: National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health

The pituitary detects when cortisol levels are high enough, then it stops sending signals. This feedback system acts like a thermostat to balance cortisol levels. It is highly controlled system.