To help diagnose Cushing's syndrome or Addison's disease
Cortisol
Cortisol
Nome formal
Cortisol
Este artigo foi revisto pela última vez em
Este artigo foi modificado pela última vez em
26 de Abril de 2018.
At a Glance
Why Get Tested?
When To Get Tested?
When your doctor suspects excess or deficient cortisol production
Sample Required?
A blood sample drawn from a vein in the arm or a urine sample; sometimes a saliva sample may be used
Accordion Title
Common Questions
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How is it used?Blood and urine tests for cortisol are used to help diagnose Cushing's syndrome and Addison's disease, two serious adrenal disorders. Some physicians are using salivary cortisol to diagnose Cushing's syndrome as well as to evaluate possible stress-related disorders, although these uses are not widespread.
Both the urine and saliva tests are most frequently used to evaluate excess cortisol production.
Once an abnormal cortisol concentration has been detected, the doctor will do additional testing to help confirm the excess or deficiency and to help determine its cause.
Dexamethasone Suppression
If there is excess cortisol production, the doctor may perform a dexamethasone suppression test to help determine whether the cause of the cortisol is related to excess ACTH production by the pituitary. This test involves giving the patient oral dexamethasone (a synthetic glucocorticoid) and then measuring their blood and urine cortisol levels. Dexamethasone suppresses ACTH production and should decrease cortisol production if the source of the excess is pituitary related. There are a variety of dosing schedules, but the medication is usually given every 6 hours for either 2 or 4 days prior to blood or urine collection. Separate 24-hour urine samples are collected prior to and throughout the testing period and then the blood and urine samples are measured for cortisol and evaluated.ACTH Stimulation
If the findings of the initial blood and/or urine tests indicate insufficient cortisol production, the doctor may order an ACTH stimulation test. This test involves measuring the concentration of cortisol in a patients blood before and after an injection of synthetic ACTH. If the adrenal glands are functioning normally, then cortisol levels will rise with the ACTH stimulation. If they are damaged, then the response will be limited. A longer version of this test (1-3 days) may be performed to help distinguish between adrenal and pituitary insufficiency. -
When is it ordered?A cortisol test may be ordered when a patient has symptoms that suggest Cushings syndrome (obesity, muscle wasting, and muscle weakness) or Addisons disease (weakness, fatigue, increased pigmentation, among others).
Suppression or stimulation testing is ordered when initial findings are abnormal. Cortisol testing may be ordered at intervals when patients are being or have been treated for Cushings syndrome or Addisons disease to monitor the effectiveness of treatment.
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What does the test result mean?In normal people, cortisol levels are very low at bedtime and at their highest just after waking. This pattern will change if a person works irregular shifts (such as the night shift) and sleeps at different times of the day. With Cushings syndrome, this pattern is typically lost.
Increased or normal cortisol concentrations in the morning along with levels that do not drop in the afternoon and evening suggest an overproduction of cortisol. If this excess cortisol is suppressed during a dexamethasone suppression test, it suggests that the excess cortisol is due to increased pituitary ACTH production. If it is not suppressed, then the increased cortisol could be due to an ACTH-producing tumor outside of the pituitary, due to a problem with the adrenal gland, or due to a medication that the patient is taking.
If the adrenal glands are overactive, then a patient may have Cushings syndrome, with symptoms and signs caused by prolonged exposure to the effects of too much cortisol. This may be due to excess production of cortisol by the adrenal glands (which is frequently due to a benign adrenal tumor) or excess ACTH stimulation (due to a pituitary or other ACTH-producing tumor). It can also be seen in patients who must take corticosteroid medications, such as those used to treat asthma. If insufficient cortisol is present and the patient responds to an ACTH stimulation test, then the problem is likely due to insufficient ACTH production by the pituitary. If cortisol levels do not respond to the ACTH stimulation test, then it is more likely that the problem is based in the adrenal glands. If the adrenal glands are underactive, due to adrenal damage or insufficient ACTH production, then the patient is said to have adrenal insufficiency. If decreased cortisol production is due to adrenal damage, then the patient is said to have Addisons disease.
Once an abnormality has been identified and associated with the pituitary gland, adrenal glands, or other cause, then the doctor may use other testing such as CT (computerized tomography) or MRI (magnetic resonance imaging) scans to locate the source of the excess (such as a pituitary, adrenal, or other tumor) and to evaluate the extent of any damage to the glands.
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Is there anything else I should know?Pregnancy, physical and emotional stress, and illness can increase cortisol levels. Cortisol levels may also increase as a result of hyperthyroidism or obesity. A number of drugs can also increase levels, particularly oral contraceptives (birth control pills), hydrocortisone (the synthetic form of cortisol), and spironolactone. Adults have slightly higher cortisol levels than children do.
Hypothyroidism may decrease cortisol levels. Drugs that may decrease levels include some steroid hormones.
Salivary cortisol testing is being used more frequently to help diagnose Cushing's syndrome and stress-related disorders but still requires specialized expertise to perform.
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Do I need both tests (blood and urine) or is one better than the other?If your doctor suspects Cushing's syndrome, usually both blood and urine are tested. Blood cortisol is easier to collect but is affected more by stress than is the urine test. Salivary cortisol may sometimes be tested instead of blood cortisol.
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How do I tell if a high cortisol level isn’t just from stress?There are several approaches that your doctor can take. The simplest involves repeating tests at a time when you feel less stressed. Your doctor can also give you varying doses of a medicine that replaces cortisol (usually dexamethasone) to see if this decreases your cortisol level. Multiple tests are often needed to tell if stress or disease is causing a high cortisol level.