The insulin STRESS test - the patient's version!
As the name of this test suggests, your body is put into a state of hypoglycaemia (low blood glucose) to create stress, so that your body’s normal hormonal response can be tested.
A few months following my pituitary surgery, I arrive at the investigation unit for my first ever insulin STRESS test. The nurse takes me to a bed in a small quiet ward and after checking my details, inserts a cannula into a vein in my arm, which allows her to obtain repeat blood samples. This blood collection starts with a baseline value of my cortisol and growth hormone, plus a blood sugar level.
I have starved since midnight, with water only and my stomach is just starting to miss breakfast, but needs must. I notice a doctor (white coat and stethoscope around his neck) is hovering nearby – must have come to find something?
Then, in through the cannula goes the insulin which reduces my blood sugar to stress the body, which will in turn stimulate my pituitary gland to produce hormones.
Within minutes or was it seconds…the most awful symptoms rush at me. I feel very, very sick, so faint, and I am shaking and sweating profusely. I curl up in a ball on the bed. This happens because your body in not used to such low levels of blood sugar.
The doctor I noticed earlier keeps coming over to me – I cannot even speak to him but plead with my eyes as best I can, that I feel so dreadful. Blood samples are taken from the cannula at 30 minute intervals for 2 hours after the injection of insulin to measure the growth hormone and my cortisol response to the insulin-induced stress of low blood sugar levels.
The doctor I mention should always be on hand through this test (with the nurse) in case you need urgent medical attention because of the low blood sugar induced.
To note here that some people will find this ‘very uncomfortable’ while others are less affected by it.
Fortunately, as soon as the required low blood sugar level is reached, the nurse appears with a cup of tea and some toast. This helps bring my blood sugar back to a normal level, and I feel a bit better.
After an hour or so, I am checked again and can leave the unit to go home. My head is thumping and I feel as if I could sleep for a week. I felt drained for the rest of the day.
I had a further insulin STRESS test a few years later and the ‘nightmare’ was the same. I would personally run a mile if the mere mention of an IST was coming my way again.
Pat McBride - Patient and Head of Patient & Family Services