Synacthen Test
At a Glance
Why Get Tested?
To help diagnose Addison's disease
When to Get Tested?
When the doctor suspects that the adrenal gland is not producing enough cortisol
Sample Required?
A blood sample is collected and then a small amount of synacthen is injected into a vein. A further blood sample is taken after 30 minutes and sometimes after 60 minutes.
The Test Sample
What is being tested?
Synacthen is a manufactured drug that acts like Adrenocorticotrophic Hormone (ACTH) by stimulating the adrenal gland to produce more cortisol. By measuring the rise in cortisol in the blood the doctor can see if the adrenal glands are secreting normal amounts of cortisol.
How is the sample collected for testing?
You will be asked to lie down for this test. A needle or small polystyrene tube (a canula) with a valve mechanism on the end is put into into a vein in your arm. The end is taped to your arm and remains in place during the test. A baseline blood sample is taken through the canula before the test. A solution containing synacthen is then injected into the vein. After 30 minutes a second sample of blood is taken. Some clinics also taken a third sample at 60 minutes. Cortisol is measured in the blood samples.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
The Test
How is it used?
The test is used to see if the adrenal glands are producing normal amounts of cortisol. When the adrenal does not produce enough cortisol and aldosterone the patient can feel tired, lethargic, sick and lose weight. Synacthen stimulates the adrenal glands to produce these steroids. If the adrenal glands are not working properly then the rise in cortisol after the injection of synacthen is either low or absent.
When is it requested?
When the doctor suspects the adrenal glands are not working properly and that the patient may have Addison’s disease.
What does the test result mean?
A normal rise in cortisol means the adrenal glands are working properly and you don’t have Addison’s disease. The laboratory and doctors will have established what a normal cortisol rise is. If the rise in cortisol is low or absent it suggests that the patient has Addison’s disease.
Is there anything else I should know?
Common Questions
Ask a Laboratory Scientist
Article Sources
NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
