Insulin Intolerance Test for Adrenal Insufficiency
Yesterday I spent a good 5 hours at Preston Hospital undergoing a not so pleasant procedure which will hopefully help the Endocrinology team to learn more about my Adrenal Insufficiency illness.
I had an Insulin Intolerance test for measuring cortisol and growth hormone production from the Pituitary gland in the brain.
I decided to explain the test and then share my own personal experience with the hope this will be both informative and help others with Adrenal Insufficiency to understand the test.
The following Information is based on the Lancashire Teaching Hospitals Medical Directorate.
What is an Insulin Tolerance Test?
This is a diagnostic test to assess if the pituitary gland is producing sufficient amounts of growth hormone and regulating the body’s production of Cortisol.
Why do we need Growth Hormone in Adulthood?
Growth hormone (GH) controls the amount of fat, muscle and water present in the body. Bone structure and heart function are also influenced by GH. Our general well-being is also thought to be controlled by GH.
Why do we need Cortisol?
Cortisol is one of the body’s main steroid hormones which is vital for life. It enables us to cope with stresses such as illness, infection, surgery and traumas. It also regulates blood pressure, the body’s fluid balance and metabolises fats, Carbohydrates and proteins.
Preparation for test
The patient must not have anything to eat or drink (except for water) from 12pm the night before the test. Adrenally insufficient patients must also stop taking any replacement steroid tablets for 24 hours before the test is scheduled.
It is also necessary to have an ECG (Heart Rhythm Tracing) before undergoing the procedure.
What the test involves
The test starts at 9 AM as cortisol levels are generally higher int he morning. The nurse will insert a cannula into the arm so that blood tests can be take and that insulin can be given through this.
The first blood test is taken 30 minutes after the cannula is inserted. This is because cortisol levels are slightly higher immediately following insertion of a cannula.
A dose of insulin Is then given through the cannula to make the blood sugar levels drop quickly causing Hypoglycaemia. Samples of blood will then be obtained from the cannula regularly.
Once adequate hypoglycaemia has been achieved diet and fluid will be offered to raise the blood sugars back to a safe rate. The nurse will also have emergency glucose on standby.
What are the side-effects
The test will make the patient feel
Lightheaded, shaky, sweaty and sleepy. -These are the normal symptoms of hypoglycaemia. the symptoms should subside after 15-20 minutes and you will then have further cortisol blood tests at several intervals.
The test should be completed by lunch time and you can restart your steroid replacement therapy and go home to rest.
My experience of the Insulin Intolerance Test.
This was my first time to have the test. I really did not know what to expect. I knew there was a risk of adrenal crisis when I became hypoglycemic, however I was reassured the procedure would be controlled by a specialist Endocrine nurse.
When I arrived I was given a bed to lie on. I was cannulated and told to trust the nurse who would be taking care of me. I was taken to get weighed so the nurse could give me the correct dose of Insulin.
My fingers were pricked and a starting blood sugar level was taken. My Cortisol and Growth Hormone (GH) was also drawn from the cannula. The insulin was then injected.
Every ten minutes the Nurse checked my sugar levels. She had to make me drop down to One on the blood sugar machine. As time went on my symptoms got worse. I felt lightheaded and sleepy and confused. I got blurred vision and could not think properly.
Once I became hypoglycemic, my bloods were taken again. Then I was given digestive biscuits and milk. I could hardly hold them but I ate the lot. It was tasty after having had no breakfast.
As my levels began to rise I had more finger pricks and more Cortisol and GH was withdrawn. After about 30 minutes my sugar levels went back to normal and I had more blood drawn every half hour.
I was exhausted and went to sleep between the tests. Once it was over, I took my Cortisol meds and had a sandwich. I went home. I felt weak and exhausted and fell asleep when I got home. I slept for 5 hours.
I could not do anything after the tests. I was physically drained…but the test went well. I did not have any adrenal crisis and they did not need to use the emergency blood sugars.
Sometimes if the test does not work..it has to be done a second time. Luckily the insulin worked first time around and I did not need to redo the test.
Thank Goodness for that.
Procedures naturally drain me as I suffer from chronic fatigue and exhaustion anyway. I think a few days of resting in bed will get me back to my normal “tired state once more”.
Having Adrenal Insufficiency is a constant battle. I never know exactly how much stress my body is under and because my hydrocortisone tablets do not mimic the natural circadian rhythm of cortisol released from the adrenals, I do suffer from extreme fatigue along with many other symptoms each day. All
I am raising funds to see a private Endocrinologist to help me have a 24 hr Day Curve and get access to the “Adrenal Pump” a medical treatment which would be life changing for me. This is not available through the NHS, but would help improve my quality of life and help me be more physically active and do more as a mum.
Thanks for reading. I hope this post helps