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Investigations to diagnose Cushing’s syndrome/ disease

Patient information A-Z

Your endocrine doctor has decided that you require several tests to find out if you are producing too much cortisol. Cortisol is one of the hormones produced by the adrenal glands. It is the body’s natural steroid hormone; it is released from the adrenal glands which sit just above the kidneys. It is a vital hormone that is responsible for enabling the body to respond to stress and illness and also regulates the immune system, blood pressure, and blood sugar levels.

Investigations involved:

Salivary cortisol x2

Cortisol can be measured through your saliva. We will provide you two tubes and information leaflet on how to collect this bedtime salivary cortisol sample.

24-hour urine free cortisol x2

This test is to measure how much cortisol your body is excreting through your urine. It is very important that the test is completed on two days, and that every time you pass urine it is all collected as this will affect the results of your test.

We will provide you two urine bottle containers with instructions on how to collect the urine samples.

Cortisol day curve

Cortisol day curve is a test which looks at your cortisol levels throughout the day by collecting hourly or two hourly blood samples. You will need to be in the Endocrine Investigation Unit for this day. We will provide you a patient information leaflet for this test.

Low-dose dexamethasone suppression testing

This is to see if your body is making too much of its natural steroid hormones. The test will involve a blood test at 09:00 then we will give you some tablets called dexamethasone, which you take strictly every six hours for 48 hours at home. We will provide you more information regarding this when we see you in our unit. Tell your specialist if you are taking any hormone tablets (eg hormone-replacement therapy) or received any hormone injection/ implants (eg contraceptive implant).

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 rearrange it.

If you need any help or any advice please ring the endocrine nurses on 01223 217848.

We are situated in the Wolfson Diabetes and Endocrine Clinic on level 2 (ground level) in the ATC on the left side of the lifts. Please report to the clinic reception and they will show you round to the endocrine unit.

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