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TRH test (thyrotrophin releasing hormone test)

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Your doctor has recommended that you take this test to help with the diagnosis and the management of your condition. Please would you read this carefully and ask us about anything that is not clear or if you would like more information.

How long will the test take?

The test will last about two hours.

Who will carry out the test?

The test will be carried out by an endocrine nurse specialist.

What will I have to do?

You will not have to do anything to prepare for this test.

    Is any drug or medicine used during this test?

    You will be given an injection of TRH (thyrotrophin releasing hormone). This is a natural hormone (chemical signal) produced by the hypothalamus. The hypothalamus is part of the brain which controls hormone function.

    What will happen during the test?

    A nurse will use a needle to put a small plastic tube into a vein in your arm. We will use this to take blood samples and to give you an injection of TRH, without the need for any more needles. After we have taken the first blood test, we will give you an injection of TRH. Over the next hour we will measure your response to the test by taking more blood samples. After we have completed the test, you will be able to go home.

    What are the possible risks or side effects of the test?

    You may experience some side effects following the TRH injection. If this happens, they will only last a very short time (less than 5 minutes). They may include a feeling that you need to pass urine, flushing, dizziness, nausea, a strange taste in your mouth, racing heart, and sometimes though rarely wheezing.

    What are the alternatives to the test?

    This test is helps us to work out why your thyroid blood test results are abnormal so that we can give you the best advice about the need for any further investigations or treatment.

    What will happen after the test?

    The blood samples are sent to the laboratory for analysis. Either the endocrine specialist nurse or your endocrinologist will discuss the results with you when they are available. They will be also discuss any further investigations or treatment you may need.

    Who do I contact if I have any questions?

    Endocrine Specialist Nurses

    Royal Sussex County Hospital
    Endocrine specialist nurse
    01273 696955 extension 64379

    Princess Royal Hospital, Haywards Heath
    Endocrine specialist nurse
    01444 441881 extension 65660

    If you have any urgent or emergency questions then your GP can advise you or they will contact the hospital on your behalf.

    This information is intended for patients receiving care in Brighton & Hove or Haywards Heath.

    The information in this leaflet is for guidance purposes only and is in no way intended to replace professional clinical advice by a qualified practitioner.

    Publication Date: July 2021

    Review Date: April 2024

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