Insulin Test (Growth Hormone Stimulation)
To investigate somatotropic function.
To investigate the hypothalamo-pituitary-adrenal system.
Fasting for 12 hrs and at rest for 30 min (although babies of under one year and hypoglycaemic subjects should be given 200 ml of milk at 5 a.m.).
- Insulin: 0.1 U/kg body weight.
In babies of under 12 months, the elderly and subjects at risk of panhypopituitarism or hypoglycaemia, the dose should be cut in half, i.e. 0.05 U/kg body weight.
- Commence the perfusion of normal saline 30 minutes before the challenge.
- Samples (dry and fluoride tubes) at T-15 and T0.
- IV injection of the correct dose of insulin.
- Samples (dry and fluoride tubes) at time intervals: T+15, T+30, T+45, T+60, T+90 and T+120 min.
Close medical supervision because of the risk of HYPOGLYCAEMIA associated with fasting coupled with the insulin: have ready a syringe containing 20 ml 20% glucose solution and a 1 mg vial glucagon.
- This test is contraindicated in the newly-born and infants.