There are3 tests that can measure cortisol
Dexamethasone suppression test (DST): Measures your body’s response to an external source of cortisol called dexamethasone. This is done through a blood test
Late-night salivary cortisol (LNSC): Measures cortisol in the saliva when cortisol should be at its lowest level
Urinary free cortisol (UFC): Measures cortisol levels in the urine over a 24-hour period
A DST can help determine if you have an underlying condition called Cushing syndrome (hypercortisolism)
Sometimes, too much cortisol is made over a long period of time due to a growth on the adrenal gland, pituitary gland, or somewhere else in the body. A DST is the most sensitive way to tell if this is the case for you.
The DST in 1, 2, 3
Here’s some important information to know about the test:
Step 1
Your healthcare provider will prescribe a 1 mg dexamethasone tablet for you to take the night before you're scheduled to have your blood drawn. The tablet should be taken between 11:00 PM and 12:00 AM.
Step 2
The following morning, you will have your blood drawn between 8:00 AM and 9:00 AM. The blood sample will then be sent to a lab.
Step 3
The lab will use your blood sample to test your cortisol level, and then the results will be sent to you and your healthcare provider. Be sure to discuss the results with your healthcare provider.
Before getting a DST, tell your healthcare provider about all medications you're currently taking and any health issues you're experiencing. These may impact the test results.
Where can I get a DST?
Ask your healthcare provider or find a specialist near you.
Understandingyour DST results
If your DST results are over 1.8 μg/dL, a condition known as Cushing syndrome (hypercortisolism) could be the cause of excess cortisol. Your healthcare provider may need to run additional tests to confirm a diagnosis.
Talk to your healthcare provider about your results and appropriate next steps.
Ready torequest a DST?
Use the Excess Cortisol Checklist to help you start the conversation with your healthcare provider.
