Insulin Stress Test

Why am I having this test?

• This test is used to check that you are able to produce enough cortisol and/or growth hormone.
• The pituitary gland regulates the release of both growth hormone and cortisol.
• The best way to determine if you have a deficiency of either of these hormones is to stimulate the pituitary gland.
• In order to do this we need to carry out an Insulin Stress Test.

Cortisol is vital for life and we need it:

• to keep our blood sugar levels stable
• to maintain blood pressure within normal limits/range
• for our metabolism, which is how we turn our food into energy
• for our immune system, which protects us from infection
• for our fluid balance, which makes sure that our body has the right amount of water

Growth hormone is needed for building and repairing cells, which are the building blocks of our bodies.

If you do not have enough cortisol or growth hormone, you may feel tired, weak and irritable.

Who carries out this test?

A nurse who specialises in endocrinology is responsible for carrying out this test.

Where is the test carried out?

You will be sent a letter with details of the test and which department you will need to attend. If you wish you may bring a companion with you and they may stay with you during the test.

How long will the test take?

The test will take approximately three to four hours in total. It is important to make sure that your blood sugar levels are normal following the test. You will be asked to remain in the ward or department until you feel well enough to leave hospital.

What do I need to do before the test?

• If you are taking the contraceptive pill or hormone replacement therapy (HRT) it may be necessary to stop these eight weeks prior to the test, as it interferes with the interpretation of the test result. Please let the endocrine specialist nurse know (contact details below) as soon as you receive your appointment letter as it may be necessary to stop them to make sure that a successful test result is obtained.
• You will need to use another method of contraception during this time.
• If you are pregnant or think that you may be pregnant, please inform the endocrine specialist nurse as soon as possible.
• You will be required to have an ECG (heart tracing) prior to this test. The ECG will be carried out in the cardiology department at the Bradford Royal Infirmary or St Luke’s Hospital.
• If you are taking steroid inhalers, steroid nasal sprays or steroid creams please do not take these for at least 24 hours before your test date. Please let the endocrine specialist nurse know as soon as you receive your appointment letter.
• If you are taking hydrocortisone, prednisolone or dexamethasone tablets, please let the endocrine specialist nurse know as soon as possible as you will be given additional instructions in your appointment letter.
• Please carry on taking any other medicines as normal, unless the endocrine specialist nurse has specifically requested you not to.
• Please bring all your medication with you.
• If you are unsure about any medication please contact the endocrine specialist nurse who is in charge of the test.
• You should not drive before or after this investigation as you may feel weak for the rest of the day.
• It is important that you have nothing to eat from 10.00pm the evening before your test. You may drink plain water freely.
• This test may not be appropriate for patients who are elderly, are known to have epilepsy or have a history of heart disease.

What happens during the test?

• You will meet the endocrine specialist nurse who is responsible for the test on your arrival in the department. The nurse will explain about the test. You will be given the opportunity to ask questions before giving consent for this test.
• You will be closely supervised by a nurse during the test.
• A cannula, a fine plastic tube, is inserted into a vein in your arm and this is then used to take blood samples. There may be some discomfort for a few seconds.
• This cannula is also used to give drugs/medicines that are required during the test.
• You will be weighed and the dose of insulin calculated from your body weight by the endocrine specialist nurse.
• You will then be given the dose of insulin through the cannula.
• Between 15-45 minutes into the test, you may feel sweaty, dizzy, trembly, restless, thirsty, drowsy, anxious, have a rapid heartbeat or palpitations. This is because your blood sugar level has fallen. This stress causes your body to release growth hormone and cortisol. You will be closely monitored and this feeling will improve during the course of the test.
• Blood tests and your blood pressure will be taken at regular intervals for 2 – 3 hours throughout the test by the nurse.
• During the course of the test, you may be given a sugary drink and biscuits to assist your blood sugar to reach a normal level again. The endocrine specialist nurse will make this decision.
• You will soon start to feel better.
• At the end of the test the cannula will be removed and a small dressing applied. The dressing may be removed when you get home.
• The endocrine specialist nurse will make sure that you have eaten, and that you are feeling well before you are allowed to go home. If you are feeling tired or unwell, you will stay on the ward/department until you feel better. The specialist nurse will arrange for a doctor to see you if necessary.

Are there any side effects?

• Occasionally the blood sugar may fall to a low level for a longer period of time and rarely people can become unconscious. If you feel very unwell during the duration of the test, you will be given a sugary drink and the test will be stopped. The endocrine specialist nurse will make this decision.
• In the extremely unlikely event that you become unconscious, you would also be given a sugar (dextrose) solution into the cannula in your arm, and the test will be stopped.
• If you become extremely unwell during the test, the endocrine specialist nurse will contact the medical team for advice.
• You may feel tired for the rest of the day following completion of the test.

What happens after the test?

• If you have been asked to stop any medicines prior to the test, the endocrine specialist nurse will advise you when to restart the medicines.
• The results will be discussed at your next clinic visit or a letter will be sent to you and your GP.
• The nurse looking after you will arrange a further appointment as required.

If you require more details please contact the Specialist Nurses in Endocrinology:
Tel: 01274 382019 Monday – Friday between 8.00am and 4.00pm except Bank Holidays