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.