Overnight Dexamethasone Suppression Test

Why am I having this test?

It is necessary for you to undergo this test to find out if your body is producing too much of the hormone cortisol (Cushing’s syndrome).

Cushing’s syndrome is the term used to describe a group of symptoms that occur when a person’s cortisol levels are too high.

What do I need to do before the test?

• If you are taking the contraceptive pill or HRT (Hormone Replacement Therapy) it may be necessary to stop these 8 weeks prior to the test, as they can interfere with the interpretation of the result. Please let the nurse know as soon as possible, as it may be necessary to stop them to make sure that a successful test result is obtained.
• You will need to use another method of contraception during this time. Alternatively, a different test may be considered.
• If you are pregnant or think that you may be pregnant, please let the nurse know as soon as possible.
• If you are taking steroid tablets, steroid nasal sprays, steroid inhalers or steroid creams please do not take these for 24 hours prior to your test date as these may interfere with the test results. Please let the nurse know beforehand.
• If you are not sure which medication to stop, please contact the nurse who will be able to advise you.
• You may eat and drink normally prior to and during the test.
• Please carry on taking any medicines that you are already on, unless we have specifically asked you not to.
• Take the 2 Dexamethasone tablets together (each tablet is 0.5 mg) between 10.00pm and midnight. This medication will have been prescribed by a member of the Endocrine team prior to the test.
• Taking the tablet with milk or an antacid may help to prevent an upset stomach or heartburn or you can take it with water/juice if you prefer.
• Attend for a blood test, at any of the places listed below, the following day between 8.45am to 9.15am. The timing of the blood test is very important.
• Take the blood request form with you.

Please make an appointment at any of the places stated below for your blood test:

• Department of Diabetes & Endocrinology at Bradford Royal Infirmary by appointment only.
• or
• GP’s surgery – You will need to make an appointment for this with the nurse.
  or
• Phlebotomy department (blood testing department) at St Luke’s Hospital, Horton Wing.
  Book via the DrDoctor system, see the link below, or by telephone 01274 365056
  https://my.drdoctor.co.uk/clinic/bth-bloodtest

What happens during the test?

• Attend for a blood test, at any of the above locations, the following day between 8.45am to 9.15am. The timing of the blood test is very important.
• Take the blood request form with you.

Are there any side effects?

Usually there are none but rarely people may experience an upset stomach or heart burn.

How long will the test take?

The test will start once you have taken the Dexamethasone tablets between 10.00pm and midnight and will finish the following morning once your blood sample has been obtained at approximately 9.00am.

What happens after the test?

• If you have been asked to stop any medicines prior to the test, the specialist nurse or doctor will let you know when to restart the medicine.
• Based on the results of the test, your doctor or specialist nurse will be able to decide whether any further investigations are required.
• The results will be discussed at your next clinic visit or a letter will be sent to you and your GP.

If you require more details please contact the Specialist Nurses in Endocrinology:
Tel: 01274 382019 Monday – Friday between 8.00am and 4.00pm except Bank Holidays