Cortisol is a hormone released by the adrenal glands that helps to regulate metabolism, immune system response, and stress levels. A low level of cortisol is a key indicator of Addison's Disease, a disorder in which the adrenal glands do not produce enough of the hormone.
When cortisol levels are too low, the body's stress response is impaired, and the body is unable to regulate its blood pressure, blood sugar levels, and other bodily functions. Symptoms of Addison's Disease can include extreme fatigue, loss of appetite, nausea, weakness, muscle and joint pain, low blood pressure, and darkening of the skin.
In addition to a low cortisol level, other tests used to diagnose Addison's Disease may include a thyroid test, adrenal gland imaging, and blood tests to measure levels of other hormones, including aldosterone.
In order to treat Addison's Disease, patients must take hormone replacement therapy, which replaces the missing cortisol and other hormones. Treatment with hormone replacement therapy can help to reduce symptoms and improve the quality of life for individuals with Addison's Disease.