Dear Doctors: I would like to know about cortisol and what it does in the body. I keep hearing that if you’re under a lot of stress, which I have been lately, your cortisol levels can go too high. What are the symptoms? How do you know if your cortisol level is OK?
Dear Reader: Cortisol is one of the hormones secreted by the adrenal glands, which sit on top of the kidneys. The adrenals are composed of two distinct types of tissue: the inner medulla and the outer cortex. It is the outer layer of tissue, also known as the adrenal cortex, that secretes the hormone cortisol.
Hormones are molecules that act as chemical messengers. They help to regulate and coordinate a wide range of functions, including metabolism, blood pressure regulation, sleep, growth, sexual development, immune function, reproduction, mood, bone health and blood sugar control. Cortisol, which is found in cells throughout the body, is involved in many of these. But it is perhaps best known for the role it plays in the body’s protective fight-or-flight response.
When the brain perceives a threat, it triggers a complex cascade of physiological reactions. Among these is a command to the adrenals to secrete more cortisol. This leads to the swift release of glucose into the blood in order to provide the large muscles of the body with as much fuel as possible for either flight or fight. The presence of cortisol also puts the brakes on insulin metabolism in order to prevent glucose from being stored. When the threat has passed, the adrenals exit their emergency mode and return to normal cortisol metabolism.
Persistent stress and anxiety can put a physical burden on the body’s emergency response systems. This includes elevated and long-term exposure to stress hormones, including cortisol. Studies have found that mean cortisol levels can increase nearly tenfold during stressful periods when compared to periods of calm. However, the physiological response to stress is quite complex and involves more than just a spike in cortisol. The possible effects of chronic stress, such as high blood pressure, poor blood glucose control, sleep disruption, depression, problems with memory and concentration, weight gain and an increased risk of cardiovascular disease cannot be attributed solely to high cortisol levels.
That said, cortisol output by the adrenal glands is affected by two diseases. When the adrenals produce an excess of cortisol, it is known as Cushing’s syndrome. Symptoms include muscle weakness, exhaustion, a pad of fat between the shoulders, muscle pain, high blood pressure and irritability. In Addison’s disease, the adrenal glands don’t make enough cortisol. This often occurs due to damage to the adrenals by an autoimmune disease. Symptoms include fatigue, unintended weight loss, low blood pressure, low blood sugar, muscle aches and pain and low mood.
Cortisol levels are easily measured with a blood, saliva or urine test. Levels of the hormone are highest in the morning and lowest at about midnight, so multiple samples may be needed. Although at-home tests are available, you will get the most accurate readings, as well as guidance regarding the results, from your health care provider.
(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)
