Cortisol is a hormone made in the adrenal glands, which are located on top of the kidneys. It's made in the part of the adrenal gland called the cortex. Cortisol is one of three glucocorticoid hormones produced in the adrenal cortex. The other two are cortisone and corticosterone. Cortisol is considered the most powerful of the three as explained in the textbook "Understanding Pathophysiology."
Stress and Cortisol
Emotional stress prompts the hypothalamus, an area in your brain, to direct the pituitary gland to send a hormone, ATCH, to the adrenal glands. ACTH stimulates the adrenals to produce the glucocorticoid hormones, especially cortisol. Physical stress acts directly on the pituitary gland to release ACTH, seemingly without the involvement of the hypothalamus.
Balance of Cortisol
In people with normal sleep cycles, the level of ACTH increases about three to five hours after they fall asleep and naturally declines through the day until the next sleep cycle. Emotional or physical stress both increase the production of ACTH, which increases the cortisol above the natural cyclical level. When this occurs, less ACTH will be produced to stimulate the production of cortisol, so the level will drop. This is a feedback system to keep the levels of cortisol in the optimum range.
Function of Cortisol
As further explained in "Understanding Pathophysiology", all the glucocorticoid hormones are directly involved in the metabolism of carbohydrates and influence the level of glucose as a result. These powerful hormones also depress some parts of the immune system while supporting others. Their purpose is to protect the body against stress, but sustained abnormal levels are dangerous. Imbalance can occur with problems in the feedback system or in the adrenal glands' ability to produce the hormones as well as from external and genetic factors.
Too Much Cortisol
Cushing's syndrome occurs when there is too much cortisol in your body. This can be from over stimulation of the adrenal glands from a pituitary disorder, excess production of cortisol in the adrenal glands or long-term use of oral or injected steroid medications. The imbalance causes a change in the body shape with fat deposits forming on the back of the neck, face and trunk. The arms and legs thin, the skin becomes fragile and stretch marks can develop, as described by the Mayo Clinic. These are the visible symptoms, but there are many things going on inside the body also.
Not Enough Cortisol
Addison's disease results from too little cortisol. In most cases, this is due to an autoimmune disorder. Lack of enough ACTH to stimulate cortisol production can also be a cause. The "Merck Manual" describes the early symptoms to include a drop in blood pressure when you stand up, fatigue and weakness. As this potentially fatal disease progresses, the skin may develop excess pigmentation in some areas and lose pigment in others. During any time of stress, the lack of cortisol becomes critical and the patient gets very ill as a result. The treatment consists of replacing the cortisol and other hormones as needed.
References
- "Understanding Pathophysiology" 3rd Edition; Sue E. Huether, RN, PhD and Kathryn L. McCance, RN, PhD; 2004
- Mayo Clinic: Cushing's syndrome
- "The Merck Manual for Healthcare Professionals": Cushing's Syndrome
- "The Merck Manual for Healthcare Professionals": Addison's Disease
- "Harrison's Principles of Internal Medicine", 17th Ed.; Anthony Fauci, Eugene Braunwald, Dennis Kasper, Stephen Hauser, Dan Longo, J. Jameson, Joseph Loscalzo; 2008
