Macimorelin stimulation test (also known as Ghryvelin stimulation test)

What is a Macimorelin stimulation test?

This is a test to measure your growth hormone levels after stimulation with the drug Macimorelin (Ghyrvelin).

Growth hormone is released from the pituitary gland. In adults it plays a role in maintaining muscle and bone mass, and affects the levels of body fat. Growth hormone may also affect energy levels, memory and your general feeling of well-being.

Do I need to prepare for the test?

You will need to fast from midnight the night before your test, as eating can affect growth hormone levels. Only plain water may be drunk during the fasting period and the test.

You will also need to avoid strenuous physical exercise for 24 hours before the test, as this can also affect growth hormone levels..

If you are on growth hormone replacement, this will need to be stopped for at least 4 weeks before the test. It may be re-started after the test unless you have been directed otherwise by your medical team.

Please bring all medication with you.

What happens during the test?

When you arrive at the Endocrine Investigation Unit you will be weighed and a cannula (a fine plastic tube) will be inserted into a vein in your arm, to allow us to take blood samples at regular intervals. The cannula will be flushed with saline to prevent it blocking.

After the first blood test you will be given a Macimorelin solution to drink, which will stimulate your body to release growth hormone. Your growth hormone levels will then be measured three times (at 45, 60 and 90 minutes)

During the test you are not permitted to eat and may only have plain water to sip.

When the test is completed the cannula will be removed and you will be given a drink and a biscuit. You may also wish to bring a snack.

How long will the test take?

Blood tests will be taken at intervals over one and a half hours (90 minutes). As you may be in the Endocrine Investigation Unit for up to two hours, you may wish to bring something to occupy you during your test such as something to read.

Will I experience any side effects?

Occasionally some people experience altered taste, nausea, headache, dizziness, tiredness. These side effects are usually mild and short-lived. If you are experiencing dizziness, you will need to wait for it to settle before you can drive home.

If you think you may be pregnant please let us know when you receive this information leaflet.

When will I get my results?

Results cannot be given to you over the telephone and will be discussed at your next clinic appointment.

Any other questions?

Please contact the Endocrine Unit on 01223 217848, 09:00 – 17:00 Monday – Friday.

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.

General information

Discounted parking is available for patients attending clinical appointments over three hours’ duration. Please present your appointment letter to receive this.

Food and drink – there is a coffee shop in the treatment centre atrium and further food and drink facilities in the main hospital concourse.

My Chart

We would encourage you to sign up for MyChart. This is the electronic patient portal at Cambridge University Hospitals that enables patients to securely access parts of their health record held within the hospital’s electronic patient record system (Epic). It is available via your home computer or mobile device

More information is available on our website: My Chart