Cortisol Day Curve

You are booked to come in for a : Cortisol Day curve (CDC)

What is a CDC?

The CDC is a test which looks at your cortisol levels throughout the day. Cortisol is a steroid hormone which is produced by the adrenal glands and 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.

Your body may be producing too much cortisol of its own and the test is to look at your cortisol levels over the course of the day, either to confirm whether this is the case, or to evaluate whether treatment you are taking to lower your cortisol level is working as it should.

How should I prepare for the test?

You need to stop any oral oestrogen therapy or implants 6 weeks prior to test as this can affect the test results. This includes the oral contraceptive pill (in which case you must take alternative precautions to avoid pregnancy) or HRT. You do not need to fast before the test.

What will happen during the test?

You should come to the ward on the date of the test, by 9am. You will have a bed to lie down in throughout the test. A cannula (a small needle with a tube attached for taking blood samples) will be placed in a vein in your arm. During the day you will take your usual hydrocortisone tablets at your usual times. Blood samples will be taken from the cannula when you arrive and at intervals during the rest of the day. Once the test is completed, the cannula will be removed and you will be able to go home.

What happens after the test?

When the results of the blood tests are available they will be reviewed by the endocrinology team. You will be notified by letter and your GP will also be informed of the results. If there are any changes to be made to your treatment or further tests that need to be organized, these will be outlined in the letter or someone from the department may contact you by telephone.

What if I have any questions?

You will see a doctor on the day of your test who should be able to answer your queries. If you have any questions before or after your test please leave a message and contact number with the endocrine department at the Hospital where your test is booked. Someone will call you back to discuss things.

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