Glucagon Stimulation Testing in Assessing for Adult Growth Hormone Deficiency: Current Status and Future Perspectives

Table 1

Recommended protocol for performing the GST in adults.

Contraindications:
Malnourished patients or patients who have not eaten for >48 h
Precautions:
Patients may feel nauseous during and after the test (administration of intravenous antiemetics can be considered)
Late hypoglycaemia may occur (patients should be advised to eat small and frequent meals after the completion of the test)
Procedure:
Ensure patient is fasted from midnight
Weigh patient
Patient in recumbent position and intravenous cannula inserted for intravenous access between 8 am to 9 am
Glucagon administered intramuscularly 1 mg (1.5 mg if patient weighs more than 90 kg)
Sampling and measurements:
Serum GH and capillary blood glucose levels at 0, 30, 60, 90, 120, 150, 180, 210, and 240 mins
Normal response:
Blood glucose usually rises to peak around 90 mins and then gradually declines (not used to interpret the test)
Serum GH: peak GH levels tend to occur between 120 to 180 mins with GH levels peaking to above 3 ng/mL
Interpretation:
In adults with GHD, peak GH levels fail to rise above 3 ng/mL