Glucagon Dose for Growth Hormone Stimulation Testing in Children
For pediatric growth hormone stimulation testing, administer glucagon at a dose of 0.03 mg/kg intramuscularly (IM) or subcutaneously (SC), with a maximum dose of 1 mg.
Dosing Algorithm
Weight-Based Dosing
Alternative Dosing Considerations
The FDA-approved glucagon labeling for diagnostic purposes does not specifically address GH stimulation testing, as it focuses on hypoglycemia treatment and gastrointestinal motility inhibition 2. However, endocrine practice guidelines consistently support the 0.03 mg/kg dosing for GH testing 1.
Administration Details
Route of administration: Intramuscular or subcutaneous injection is standard for GH stimulation testing 1. The intramuscular route is preferred over intravenous administration, as IM glucagon demonstrates superior GH-releasing activity compared to IV administration 3.
Timing of blood sampling: Draw blood samples at baseline (time 0), then at 30,60,90,120,150,180,210, and 240 minutes after glucagon administration 1.
Interpretation cutoffs: A peak GH response >3 μg/L is generally considered normal, though BMI-adjusted cutoffs should be applied as obesity blunts GH response 1, 4.
Critical Safety Considerations
Hypoglycemia Risk
Hypoglycemia occurs in approximately 34% of children undergoing low-dose glucagon stimulation testing 5. This risk is particularly elevated in:
- Children <8 years old (odds ratio 2.63) 5
- Younger prepubertal children (median age 5.1 years vs 9.6 years in those without hypoglycemia) 5
Monitoring Requirements
- Blood glucose monitoring is essential throughout the test 5
- Monitor for falling glucose trends, especially at 180 minutes (33% of children show declining glucose at test end) 5
- Have IV dextrose immediately available
- Glucagon may cause nausea and vomiting due to delayed gastric emptying 6
Contraindications
Do not perform glucagon stimulation testing in patients with:
- Pheochromocytoma (risk of hypertensive crisis) 2
- Insulinoma (risk of severe hypoglycemia) 2
- Known glucagon hypersensitivity 2
Test Performance Characteristics
When used as the first stimulation test, glucagon demonstrates superior performance compared to arginine, with a discordant result rate of 37.4% versus 50.7% for arginine 7. This suggests glucagon should be the preferred initial test when two stimulation tests are required for GHD diagnosis.
The glucagon test evaluates the complete hypothalamic-somatotroph axis 4, making it particularly valuable after cranial radiation therapy where GHRH-based tests may yield false-negative results 4.
Reconstitution Instructions
Using the supplied prefilled syringe containing 1 mL diluent:
- Inject all diluent into the vial containing glucagon powder
- Swirl gently until completely dissolved (do not shake)
- Inspect for clarity—solution should be water-like without particles
- Withdraw the calculated dose immediately after reconstitution
- Administer within minutes; do not store reconstituted solution 2
Post-Test Management
Once the test is complete and the child can safely swallow, provide oral carbohydrates to restore liver glycogen and prevent recurrent hypoglycemia 8, 2. This is particularly important given the prolonged duration of the test (up to 4 hours) and the significant hypoglycemia risk in young children.