Short Synacthen Test

Patient Experience

  • Reference Number: HEY1175/2020
  • Departments: Diabetes
  • Last Updated: 4 March 2022


This leaflet has been produced to give you general information. Most of your questions should be answered by this leaflet. It is not intended to replace the discussion between you and the healthcare team, but may act as a starting point for discussion. If after reading it you have any concerns or require further explanation, please discuss this with a member of the healthcare team.

What is Short Synacthen Test?

Short synacthen test checks if your adrenal glands are producing enough steroid hormone called cortisol. A hormone is a chemical produced by a gland to send important messages to different parts of the body. Normally, you have two adrenal glands that lay just above each kidney.

Cortisol is the most important hormone produced by the adrenal gland. Cortisol production is controlled by the pituitary gland (a small, pea-sized gland just below the brain). The pituitary gland produces a regulating hormone called adrenocorticotrophic hormone (ACTH). ACTH causes the adrenal glands to make cortisol. Diseases of the adrenal gland or the pituitary can cause steroid hormone deficiency.

Cortisol is vital for health. It has many functions which include:

  • helping to regulate blood pressure
  • helping to regulate the immune system
  • helping to balance the effect of insulin in regulating the blood sugar level
  • helping the body to respond to stress

‘Hypoadrenalism’ means deficiency of cortisol. When this happens due to diseases of the adrenal gland, the condition is known as Addison’s disease. When it occurs due to diseases of the pituitary, it is called central hypoadrenalism or secondary hypoadrenalism.

A one-off measurement of blood cortisol is not good enough to make a diagnosis. Cortisol may be low from time to time in healthy people. As steroid deficiency needs long-term (often lifelong) treatment, a reliable test is needed so that we can be confident about the diagnosis. The short synacthen test is one of the commonest tests used to check cortisol function.

With the short synacthen test, the adrenal gland is stimulated by an injection of a drug (synacthen), which is chemically similar to ACTH. If the adrenal glands are working normally, blood samples taken shortly after synacthen should show a rise in cortisol. If you have hypoadrenalism, you may not have a rise in blood cortisol following the injection.

The short synacthen test can tell us if you have steroid deficiency most of the time but sometimes, it could give borderline results. Your doctor will advise what to do if the test is borderline.

Can there be any complications or risks?

Synacthen has been used for nearly 50 years. It is very safe and side effects are extremely uncommon. It would be unusual for you to experience any side effects.

However, according to the manufacturer, known reported side effects could include skin reactions, rashes and hives, allergic reactions, breathing difficulties, dizziness, nausea, vomiting. These side effects occur rarely, so it is not possible to foresee patients experiencing them.

Synacthen does not stay in the body for a long time. Most of the injected synacthen leaves the body in minutes. Any side effects that may be related to synacthen are not expected after one day.

How do I prepare for the Short Synacthen Test?

Please read this information leaflet carefully.  Share the information it contains with your partner and family (if you wish) so that they can be of help and support.  There may be information they need to know.

  • The test should not be performed if you are unwell. If your test is organised by a consultant or a clinical nurse specialist from Endocrinology, please contact us to reschedule.
  • If you take hydrocortisone, do not take the dose on the evening before and morning of the test. You should bring your morning dose with you to the appointment.
  • If you are taking inhaled steroids (e.g. for asthma); other steroid tablets such as prednisolone or dexamethasone; oral contraceptive agents (birth control pills) or hormone replacement therapy (HRT), please tell us.
  • You may eat and drink normally prior to the test.
  • The test takes approximately 45 minutes, you may wish to bring a book or magazine to read whilst you are waiting.

What will happen?

  • A blood test is taken from a vein in your arm to measure cortisol.
  • You will be given an injection of synacthen, which stimulates the adrenal glands to produce Cortisol.
  • You will wait in the waiting room for 30 minutes.
  • A final blood test will be taken for cortisol, this completes the test.

What will happen afterwards?

You may return home following the test and resume normal activities.

You will receive your test result from the doctors or clinical nurse specialists who ordered this test. This may be by a face-to-face consultation or a phone call or by letter.

Contact details

If you need further advice on the issues contained in this leaflet, please contact your healthcare team.

If your test is being organised at the Allam Diabetes Centre

Please contact the department on 01482 311824 or 01482 311819.

If your test is being organised at the Medical Day Unit

Please contact the Medical Day Unit on (01482) 674640 or 676423

If your test is being done while you are an inpatient, you should ask the doctors who is looking after you.

This leaflet was produced by the Department of Diabetes, Endocrinology and Metabolism, Hull University Teaching Hospitals NHS Trust and will be reviewed in October 2023

General Advice and Consent

Most of your questions should have been answered by this leaflet, but remember that this is only a starting point for discussion with the healthcare team.

Consent to treatment

Before any doctor, nurse or therapist examines or treats you, they must seek your consent or permission. In order to make a decision, you need to have information from health professionals about the treatment or investigation which is being offered to you. You should always ask them more questions if you do not understand or if you want more information.

The information you receive should be about your condition, the alternatives available to you, and whether it carries risks as well as the benefits. What is important is that your consent is genuine or valid. That means:

  • you must be able to give your consent
  • you must be given enough information to enable you to make a decision
  • you must be acting under your own free will and not under the strong influence of another person

Information about you

We collect and use your information to provide you with care and treatment. As part of your care, information about you will be shared between members of a healthcare team, some of whom you may not meet. Your information may also be used to help train staff, to check the quality of our care, to manage and plan the health service, and to help with research. Wherever possible we use anonymous data.

We may pass on relevant information to other health organisations that provide you with care. All information is treated as strictly confidential and is not given to anyone who does not need it. If you have any concerns please ask your doctor, or the person caring for you.

Under the General Data Protection Regulation and the Data Protection Act 2018 we are responsible for maintaining the confidentiality of any information we hold about you. For further information visit the following page: Confidential Information about You.

If you or your carer needs information about your health and wellbeing and about your care and treatment in a different format, such as large print, braille or audio, due to disability, impairment or sensory loss, please advise a member of staff and this can be arranged.

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