Growth hormone stimulation test
Last updated: Monday, 22, March, 2004
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| Item | Process |
|---|---|
| Specimen | The patient should be fasting. 2 mL blood in a lithium heparin or plain tube taken at intervals, as indicated. |
| Method | Glucose - spectrophotometry. Growth hormone - immunoassay. |
| Protocol | Exercise: specimen taken 15 and 30 minutes after vigorous exercise. Arginine-insulin: specimens are taken at 15 minute intervals during and after an infusion of arginine hydrochloride (0.5 g/kg body weight to a maximum of 30 g) followed after 90 minutes by an injection of insulin (0.075 U/kg body weight). The patient must be observed continually for hypoglycaemia by a medical officer; glucose must be available for IV use. L-dopa and clonidine are also used in provocative tests. |
| Reference Interval | Peak growth hormone >20 mU/L (10 µg/L). |
| Application | Diagnosis of growth hormone deficiency. The arginine-insulin test may be done as an initial test or following a negative exercise test. |
| Interpretation | Plasma glucose must decrease to <2.2 mmol/L for the arginine-insulin test to be valid. A growth hormone level of >20 mU/L, with either test, excludes growth hormone deficiency. |
| Reference | Hintz RL. J Pediatr Endocrinol Metab 2003; 3: 631-5. |