Purpose
To investigate somatotropic function in growth retardation by using an associated assay to stimulate growth hormone secretion. This test associates the effect of Gucagon on the alpha-adrenergic receptors, involved in GH-RH secretion, and beta blocking agents’ inhibitor effect on the somatostatine secretion, consequence of a higher response in hCG. This is a front line test among the most efficient.
Subject preparation
- Fasting for 12 hours. Children can eat before the beginning of the challenge
- Away from any stimulation at least 2 hours prior the beginning of the challenge
Product
- Glucagon Novo® , Novo Nordisk Pharmaceutical SA (1mg bottle)
- Propranolol, Avlocardyl®, Astra Zeneca (40 mg tablet or 5mg/5ml vial – oral administration)
Dose
- Glucagon (Glucagon Novo®) : 1 mg or 0.5mg if child is less than 1 year old, by slow IV injection.
- Propranolol (Avlocardyl®): 0.75 mg /kg body weight without exceeding 40 mg, oral administration.
Protocol
- Commence the perfusion of normal saline 30 minutes before the challenge.
- Blood samples (1 dry tube and 1 fluoride tube) at T-30 min.
- Oral administration of the correct dose of propranolol.
- Blood samples (1 dry tube and 1 fluoride tube) at T0.
- IM injection of 1 mg glucagon.
- Blood samples (1 dry tube and 1 fluoride for each time interval) at the time intervals: T+30, T+60, T+90, T+120, T+150 and T+180 min.
Samples
After centrifugation, draw off the serum and plasma. Freeze the serum and store plasma at +4°C.
Side effects
Close medical supervision (with regular measurements of pulse and blood pressure) due to the risk of:
- Bradycardia and faintness due to the propranolol.
- Vomiting and hypoglycaemia at the end of the glucagon challenge.
Contraindications
- Asthma.
- Heart failure.