Skip to content

Information and Resources

Font Size
A
A
A

Overnight Dexamethasone Suppression Test

Results

The overnight dexamethasone suppression test involves taking a dose of a corticosteroid medicine called dexamethasone to see how it affects the level of a hormone called cortisol in the blood. This test screens for Cushing's syndrome, a condition in which excess amounts of cortisol are being produced by the adrenal glands. Test results are usually available in a few days.

An abnormal test result may mean that further testing is needed to identify Cushing's syndrome. Likewise, a normal test result means that you do not have Cushing's syndrome. Cushing's syndrome can be hard to diagnose, so an endocrinologist should be consulted if test results are uncertain or if the test results do not help explain your symptoms.

The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.

Normal

Overnight dexamethasone suppression test 1
Normal:

Cortisol level is less than 5 micrograms per deciliter (mcg/dL) or less than 138 nanomoles per liter (nmol/L).

High values

High cortisol levels may be caused by:

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

Some people may quickly process (metabolize) the dose of dexamethasone. In these people, cortisol levels will not drop unless a higher dose of the medicine is given.

WebMD Medical Reference from Healthwise

Last Updated: May 17, 2012
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

Hot Topics

WebMD Video: Now Playing

Click here to wach video: Dirty Truth About Hand Washing

Which sex is the worst about washing up? Why is it so important? We’ve got the dirty truth on how and when to wash your hands.

Click here to watch video: Dirty Truth About Hand Washing

Popular Slideshows & Tools on WebMD

feet
Solutions for 19 types.
MS Overview
Recognizing symptoms.
pregnancy test and calendar
Helping you get pregnant.
man rubbing painful knee
A visual guide.
lone star tick
How to identify that bite.
woman standing behind curtains
How it affects you.
brain scan with soda
Tips to avoid complications.
row of colored highlighter pens
Tips for living better.
human lungs
Symptoms, causes, treatments.
woman dreaming
What Do Your Dreams Say About You?
two male hands
Test your knowledge.

Pollen counts, treatment tips, and more.

It's nothing to sneeze at.

Loading ...

Sending your email...

This feature is temporarily unavailable. Please try again later.

Thanks!

Now check your email account on your mobile phone to download your new app.

Women's Health Newsletter

Find out what women really need.