Cortisol vs Cortisone: Understanding the Difference
Cortisol and cortisone are often used interchangeably in everyday conversation, but they are not the same molecule. Cortisol is the primary glucocorticoid hormone produced by the adrenal glands, while cortisone is a closely related steroid that the body can convert to and from cortisol. Understanding the distinction matters for interpreting laboratory results and for understanding how certain medications work.
Key takeaways
- Cortisol is the main active glucocorticoid hormone made by the adrenal glands, while cortisone is a related steroid that is largely inactive until converted to cortisol.
- The enzyme 11-beta-hydroxysteroid dehydrogenase (11β-HSD) interconverts cortisol and cortisone in tissues, helping regulate local hormone activity.
- Standard blood and saliva tests typically measure cortisol, not cortisone, because cortisol is the primary circulating active hormone.
- Cortisone is also available as a medication, but it must be converted by the body into cortisol to have a glucocorticoid effect.
What Is Cortisol?
Cortisol is a steroid hormone produced by the adrenal cortex, the outer layer of the adrenal glands. It belongs to the glucocorticoid class and plays a central role in the body's response to stress, in glucose metabolism, in blood pressure regulation, and in the modulation of inflammation and immune function. Cortisol is released in a daily rhythm, typically peaking in the early morning and reaching its lowest point around midnight.
Because cortisol is the primary active glucocorticoid in humans, most clinical laboratory tests are designed to measure it directly. Blood, saliva, and urine tests can assess cortisol levels at a single point in time or over a 24-hour period. These tests are used when a clinician suspects conditions such as adrenal insufficiency, Cushing syndrome, or other disorders of the hypothalamic-pituitary-adrenal (HPA) axis.
What Is Cortisone?
Cortisone is a steroid hormone that is structurally very similar to cortisol. The key difference is a chemical modification at one position on the steroid ring, which makes cortisone largely inactive on its own. In the body, cortisone can be converted into cortisol by the enzyme 11-beta-hydroxysteroid dehydrogenase type 1 (11β-HSD1). The reverse reaction, converting cortisol back to cortisone, is carried out by 11β-HSD2.
This interconversion acts like a local switch that adjusts how much active glucocorticoid is available in specific tissues. Because cortisone itself has little direct glucocorticoid activity, it is not the main hormone measured in routine laboratory testing. Instead, it is often described as a precursor or storage form that can be activated where needed.
How the Body Converts Cortisol and Cortisone
The balance between cortisol and cortisone is maintained by the two isoforms of 11-beta-hydroxysteroid dehydrogenase. In tissues such as the liver and adipose tissue, 11β-HSD1 predominantly converts cortisone to cortisol, increasing local glucocorticoid action. In the kidney and some other tissues, 11β-HSD2 does the opposite, converting cortisol to cortisone and protecting mineralocorticoid receptors from excessive cortisol exposure.
This system allows the body to fine-tune glucocorticoid activity at the tissue level without necessarily changing circulating cortisol concentrations. It also explains why some tissues can respond to glucocorticoids even when blood cortisol levels appear normal. Disruptions in these enzymes have been studied in relation to metabolic and blood pressure regulation.
Cortisone as a Medication
Cortisone is also manufactured as a medication, usually in the form of cortisone acetate. When given as a drug, it is considered a prodrug because the body must convert it into cortisol for it to produce glucocorticoid effects. This conversion occurs mainly in the liver. Other synthetic glucocorticoids, such as prednisone and prednisolone, follow similar activation principles.
Clinicians may prescribe cortisone or related steroids for inflammatory and autoimmune conditions, adrenal insufficiency, and certain allergic or dermatologic disorders. Because these medications can suppress the HPA axis with prolonged use, dosing and tapering are managed carefully. Laboratory testing may be used to monitor adrenal function before, during, or after treatment.
Frequently Asked Questions
Are cortisol and cortisone the same thing?
No. Cortisol is the primary active glucocorticoid hormone produced by the adrenal glands. Cortisone is a closely related steroid that is largely inactive until the body converts it into cortisol.
Which one do blood tests usually measure?
Most standard blood, saliva, and urine tests measure cortisol, because it is the main circulating active glucocorticoid. Cortisone is not typically the primary target of routine testing.
Why does the body convert cortisol to cortisone?
Converting cortisol to cortisone reduces local glucocorticoid activity and protects certain tissues, such as the kidney, from excessive cortisol effects. The reverse conversion provides active cortisol where it is needed.
Is cortisone medication the same as natural cortisone?
Cortisone medications contain the same steroid molecule, often as cortisone acetate. As a medication, cortisone acts as a prodrug that the body must convert into cortisol to produce its effects.
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