Dear Dr. Roach: I’ve been feeling just awful. My doctor put me through the normal tests, and all were good. A neurologist recommended that I get a cortisol test. I did, and it showed a high cortisol level. I’d never heard of this. Would you explain what high cortisol is, how it is treated, and if there are any natural cures or therapies? — S.K.

Answer: Cortisol is a critical hormone that is needed for the function of many body systems. Without cortisone, the body cannot respond to stress, and a stressful event can literally kill a patient.

A medical condition called Addison’s disease is when the body cannot make cortisol (a type of steroid called a glucocorticoid). People with this condition need to take replacement cortisol or a synthetic form daily, and they need to take higher doses when under stress to prevent this. Addison’s disease was most often caused by tuberculosis, but the leading cause of Addison’s is an autoimmune disease of the adrenal cortex (where cortisone is made). People usually feel weak and tired with Addison’s.

Cushing’s syndrome is the opposite, where the body makes too much cortisone. The most common cause for this is a benign tumor. In Cushing’s syndrome, the list of possible symptoms is seemingly endless, but fatigue and muscle weakness, weight gain in the abdomen but muscle loss in the limbs, and skin and hair changes are common. People can experience the same problem when taking high doses of cortisol or similar steroids such as prednisone, hydrocortisone or dexamethasone.

A cortisol level of 18 isn’t diagnostic of Cushing’s but almost certainly excludes Addison’s disease. Depending on the time of day, cortisol levels can be between 5-25 mcg/dL, so a level of 18 mcg/dL in the morning may be normal. People with high levels of stress tend to have high to normal cortisol levels.

In contrast, a level of 18 mcg/dL at bedtime would be a very concerning sign for Cushing’s. If your doctors were worried about Cushing’s, additional testing could be recommended such as a 24-hour urine cortisol test, a bedtime salivary cortisol test, or checking the blood cortisol after suppressing its release with a medication that stops cortisol release.

An endocrinologist is the expert in making the diagnosis and treating diseases of the adrenal hormones, including Addison’s and Cushing’s.