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Short synacthen test

Patient information A-Z

Your endocrine doctor has recommended this test for you. Your appointment letter will inform you if you need to fast for this test.

What is a short synacthen test?

This is to see if your adrenal glands are producing enough of a hormone called cortisol, which is the body’s natural steroid hormone. It is released from the adrenal glands which sit just above the kidneys.

Cortisol is a vital hormone that is responsible for enabling the body to respond to stress and illness and also regulates your immune system, blood pressure and blood sugar levels.

Cortisol production is controlled by the pituitary gland which is a tiny pea sized gland just underneath the brain. A problem with either the pituitary or adrenal glands can cause low cortisol levels.

Do I need to prepare for the test?

If you are taking hydrocortisone, prednisolone or other steroids do not take them on the morning of your test. If you are on steroids and have been unwell and needed to increase your dose in the week before your appointment then please contact us for advice before your visit.

Please bring your hydrocortisone, prednisolone or other steroid medication with you; you will be able to take it normally after the test is completed. You can take your other regular medication (see exceptions below). Please bring a list of all your medications with you.


If you are using the oral contraceptive pill, or oral HRT you will need to stop them for six weeks prior to your test as they can affect results. If you are using an HRT patch or pessaries you may continue to do so. If you are stopping the contraceptive pill you must use an alternative contraceptive to avoid pregnancy.

If you think you may be pregnant please let us know when you receive this information leaflet.


If you are using Testim or Testogel please do not apply it on the morning of this test.

If you are using Tostran you should apply it as usual.

What happens during the test?

We will take a sample of blood to measure your cortisol levels.

You will then be given an injection of synacthen either intravenously, or into the muscle in the top of your arm. If you are on Warfarin, we will give the synacthen intravenously. After 30 minutes another blood sample will be taken to see if your adrenal glands have responded appropriately.

The test will take approximately one hour in total. You will be able to drive home afterwards.

Are there any side effects?

You may feel light headed or faint, experience a warm sensation or slight nausea when we inject the hormone, but these feelings should subside quickly. Please tell the doctor or nurse if you suffer from asthma or any previous allergic reactions you have had. Extremely rarely there is a risk of allergic reaction to this test.

When will I get my results?

Results cannot be given over the telephone. They will be reviewed by an endocrine doctor and discussed at your next clinic appointment, or as previously arranged with your clinician.

Any other questions?

Please contact the Endocrine Unit on 01223 217848. Monday to Friday – 09:00 to 17:00.

The timing of the test is important so please attend at the time specified on your appointment letter. If you are unable to attend your appointment please contact the Endocrine Unit to re-arrange it.

General information

Discounted parking is available for patients attending clinic appointments over three hours duration. Please present your appointment letter to the reception desk in the treatment centre atrium to receive this.

Food & drink - there is a coffee shop in the Treatment Centre Atrium and further food and drink facilities in the main hospital concourse.

We are smoke-free

Smoking is not allowed anywhere on the hospital campus. For advice and support in quitting, contact your GP or the free NHS stop smoking helpline on 0800 169 0 169.

Other formats

Help accessing this information in other formats is available. To find out more about the services we provide, please visit our patient information help page (see link below) or telephone 01223 256998.

Contact us

Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge

Telephone +44 (0)1223 245151