Cortisol is a hormone (in the family of the glucocorticoids), made in the adrenal gland then released into the blood. Almost every cell in the body needs cortisol, so the action it can have on the different cells depends on which body system it is affecting. These actions include controlling the body’s blood sugar levels, regulating metabolism, acting as an anti-inflammatory, influencing memory formation, controlling salt and water balance, influencing blood pressure and helping development of the fetus in pregnant women.
Blood levels of cortisol can vary, but in general cortisol level are higher in the morning when we wake up, and then fall throughout the day. In people that work at night, this pattern is reversed, so the timing of cortisol release is clearly linked to daily activity patterns. In addition, in response to stress, extra cortisol is released to help the body to respond appropriately.
The secretion of cortisol is mainly controlled by the hypothalamus in the brain, the pituitary gland and the adrenal glands. This is called the hypothalamic–pituitary–adrenal axis (or the HPA axis). When cortisol levels in the blood are low, a group of cells in a region of the brain called the hypothalamus releases a hormone called corticotrophin-releasing hormone, which causes the pituitary gland to secrete another hormone, adrenocorticotropic hormone (ACTH) into the bloodstream. Elevated levels of ACTH are detected in the adrenal glands and stimulate the secretion of cortisol, causing blood levels of cortisol to rise. As the cortisol levels rise, they start to block the release of corticotrophin-releasing hormone from the hypothalamus and ACTH from the pituitary. As a result, the ACTH levels start to drop, which then leads to a drop-in cortisol levels. This is called a negative feedback loop.
Elevated levels of Cortisol
Too much cortisol over a prolonged period can lead to a condition called Cushing’s syndrome. This can be caused by a wide range of factors, such as a tumor that produces ATCH (and therefore increases cortisol secretion), or taking certain types of drugs or prolonged chronic stress. The symptoms include:
- rapid weight gain mainly in the face, chest and abdomen contrasted with slender arms and legs
- flushed and round face
- high blood pressure
- osteoporosis
- skin changes (bruises and purple stretch marks)
- muscle weakness
- mood swings, which show as anxiety, depression or irritability
- increased thirst and frequency of urination.
High cortisol levels over a prolonged time can also cause lack of sex drive and, in women, periods can become irregular, less frequent or stop altogether (amenorrhea). In addition, there has been a long-standing association between raised or impaired regulation of cortisol levels and several psychiatric conditions such as anxiety and depression.
Low levels of Cortisol
Too little cortisol can be due to a condition called Adrenal Fatigue or if very server Addison’s disease. It has many causes, all rare, including prolonged elevated level of stress on your body stress and/or damage to the adrenal glands by autoimmune disease. The onset of symptoms is often very gradual. Symptoms may include fatigue, dizziness (especially upon standing), weight loss, muscle weakness, mood changes and the darkening of regions of the skin.
Listed below are some common symptoms of very low cortisol:
- Dizziness
- Fatigue
- Unexplained weight loss
- Dark rings under the eyes
- Palpitations
- Cravings for salty food
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