Cortisone is often used in everyday language to refer to its active counterpart, cortisol. Cortisol is a powerful, naturally produced steroid hormone belonging to the class of glucocorticoids. As a fat-soluble molecule, it travels through the bloodstream and affects nearly every cell in the body. It is often called the “stress hormone” because its release is central to the body’s response to physical or psychological strain, helping the body manage and adapt to perceived threats by rapidly mobilizing resources.
The Body’s Natural Cortisol Production and Release
Cortisol production originates in the adrenal glands, two small organs situated on top of the kidneys. The release of this hormone is tightly controlled by the Hypothalamic-Pituitary-Adrenal (HPA) axis. When the brain senses a threat, the hypothalamus releases corticotropin-releasing hormone. This prompts the pituitary gland to send adrenocorticotropic hormone (ACTH) to the adrenal glands, signaling the adrenal cortex to synthesize and release cortisol into the bloodstream.
Cortisol levels naturally fluctuate throughout the day in a distinct diurnal rhythm. Levels peak in the early morning to help the body wake up and gradually decline toward the evening. During moments of acute physical or psychological stress, this basal rhythm is overridden, causing a surge of cortisol. This sustained release helps the body remain alert and prepared following the initial “fight or flight” burst of adrenaline.
The body naturally produces a small amount of cortisone, which is an inactive form chemically similar to cortisol. Cortisone is converted into active cortisol within certain tissues by the enzyme 11-beta-hydroxysteroid dehydrogenase type 1, allowing for local activation. Conversely, other enzymes can convert active cortisol back into inactive cortisone, particularly in the kidneys. This conversion process helps regulate the overall concentration and maintain a precise balance of the active hormone.
Managing Metabolism and Inflammation
Cortisol’s most significant biological actions center on regulating energy and modulating the immune system. Metabolically, cortisol is a primary driver of gluconeogenesis, the process of generating new glucose in the liver from non-carbohydrate sources like amino acids and fats. This mechanism ensures that the brain and muscles have a constant and readily available supply of energy.
The hormone also influences the breakdown of stored energy reserves throughout the body. It promotes the breakdown of fats into fatty acids (lipolysis) and the breakdown of proteins in muscle tissue (proteolysis) to provide the necessary building blocks for glucose production. Cortisol also reduces the uptake of glucose by tissues like muscle and fat, conserving blood sugar for the central nervous system. These actions collectively increase blood sugar levels, supporting the body’s heightened energy demands.
Cortisol plays a powerful role in regulating the immune system by functioning as an anti-inflammatory agent. It works by inhibiting the release of chemicals that promote inflammation, such as cytokines and prostaglandins. Suppressing these signals helps prevent an overactive or damaging immune response. This dampening effect is a protective mechanism, keeping the body’s reaction measured and localized during injury or infection.
Cortisone as a Therapeutic Drug
Synthetic versions of cortisone and cortisol, generally called corticosteroids, are widely used in medicine because they mimic the body’s anti-inflammatory effects. When administered, synthetic cortisone is often given in much higher concentrations than the body naturally produces. This allows it to exert a potent and localized effect, reducing severe inflammation and suppressing harmful immune responses.
A common application is a cortisone injection, where the drug is delivered directly into a localized area, such as an inflamed joint, bursa, or tendon. This localized delivery provides targeted relief for conditions like arthritis or tendonitis without the systemic side effects of oral medication. Topical creams and ointments containing hydrocortisone, the pharmaceutical name for cortisol, are also used. These treat inflammatory skin conditions such as rashes and eczema by exploiting the hormone’s ability to calm the immune system and reduce swelling.
What Happens When Cortisol Levels Are Imbalanced
Failure of the body’s natural regulatory system for cortisol can lead to two main chronic conditions. Hypercortisolism, or chronic excess cortisol, is associated with Cushing’s Syndrome. This can be caused by tumors in the pituitary or adrenal glands, or by long-term, high-dose use of corticosteroid medications. Chronic overexposure leads to symptoms like high blood sugar, weight gain, muscle weakness, and impaired immune function.
Conversely, hypocortisolism, a chronic deficiency in cortisol, characterizes Addison’s disease. This is commonly an autoimmune disorder that damages the adrenal glands. The lack of sufficient cortisol results in symptoms such as chronic fatigue, unintended weight loss, low blood pressure, and a reduced ability to manage stress. Both conditions demonstrate the importance of maintaining the precise balance of this glucocorticoid hormone for overall health.