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Back| Drug Name | Method | Peak Time | Mechanism |
|---|---|---|---|
| Clonidine | 4μg/kg or 0.15mg/m2 orally, blood samples taken at 0, 30, 60, 90 min after administration to measure GH | 60~90 min | α-Adrenergic receptor agonist stimulates hypothalamic GHRH release |
| L-Dopa | 10mg/kg or 0.5g/1.73m2, blood samples taken before and after administration, same timing as above | 60~90 min | Stimulates hypothalamic GHRH release via dopaminergic pathways |
| Arginine | 0.5g/kg IV infusion, max dose 30g, infused over 30 min, blood samples taken before and at 30, 60, 90, 120 min after infusion | 60~90 min | Inhibits hypothalamic somatostatin secretion via α-receptor mediation |
| Insulin | Regular insulin 0.05U/kg, diluted in saline and injected IV, blood samples taken before and at 15, 30, 45, 60 min after injection | 15~30 min | Induces hypoglycemia to stimulate GH secretion. Effective when blood glucose drops to 50% of baseline |
Explanation
Due to different pathways of GH response to various drugs, the sensitivity and specificity of each test vary. Therefore, at least two drugs with different mechanisms are usually used for stimulation tests. Fasting for more than 8 hours is required before the GH stimulation test.
If the GH peak value in both tests is <5μg/L, it indicates complete GH deficiency;
GH peak value between 5.1~9.9μg/L indicates partial GH deficiency;
GH peak value ≥10μg/L is considered normal.
