Growth hormone day curve

Investigation Protocol


To assess clinical severity of growth hormone excess in acromegaly and to assess response to medical therapy.


Patient may eat and drink, and take all medications as normal on the day of the test, though patients are asked to bring all their medication with them, for this to be documented during the day curve.


Insert an indwelling cannula gauge 20 with a three-way tap. This is to reduce possibility of stressful venepuncture causing inappropriately high growth hormone levels. Wait 15 minutes before taking first blood sample.

Using the vacutainer connector system or a syringe fill one plain clot bottle for each sample taken. This should be clearly marked with the patient’s details, date and time of sample.

After each blood sample is taken, flush the cannula with 2mls sodium chloride. Prior to taking each blood sample, withdraw 2mls and discard to remove the sodium chloride flush. Samples for growth hormone levels are taken at 9am, 11am, 1pm, 3pm and 5pm. It is important to clearly mark patient’s details, date and time of sample on each bottle.

At end of test remove cannula and patient may go home.

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Patient information sheet

Growth hormone day curve 

Your doctor has referred you to have a growth hormone curve. This is performed over a day and will tell us if your levels of growth hormone are satisfactory and that your acromegaly is under control.

During the test blood samples will be taken at two hourly intervals. To allow this to happen easily with the minimum of discomfort & stress (which might affect your growth hormone levels), we will be inserting a small tube (a cannula) into a vein in your arm at the start of the test. We will be taking a sample of blood at 9am, 11am, 1pm, 3pm and 5pm. You will be resting in a reclining chair throughout the test.

You may eat and drink as normal on the day of the test. If you are in the unit over the lunch period you will be offered something to eat. You do not have to stay in the unit for the whole day but you may do so if you choose.

Please take all your medication as normal on the day of this test.

You should expect your stay at the hospital to last until 5pm. You may wish to bring a book or magazine to read. We do have a radio, or you can access Patientline; alternatively you may like to bring your own personal radio/cd player (please bring your own headphones). You may bring someone to stay with you during the test but there is not enough space for more than one person.

Children are discouraged, as this can be disruptive to other patients. However, if this poses a particular problem for you please discuss this with the senior nurse in the unit. You should be able to undertake normal activities after the test is finished and it should not interfere with your ability to drive home. 

If you have any queries about the test, please contact: 

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