GH measurements are used during investigations of short stature, adult GH deficiency, acromegaly, gigantism and assessment of hypothalamic-pituitary function. Single GH estimates are seldom useful. If acromegaly is being considered, IGF-1 is the preferred test.
Patient should be unstressed and preferably fasted prior to sampling. Repeated sampling, stimulation and suppression tests are usually necessary.
It is essential to state the age of the patient and percentage above ideal body weight in order to facilitate interpretation of results.
Note: Hypothyroidism must be corrected before carrying out tests of growth hormone secretion. Other drugs, particularly progestogens, chlorpromazine, L-Dopa, etc should be avoided.
Specimen Collection Protocols:
See the specific instructions for particular dynamic tests.
Note that all samples, including those in a series, must have individual unique lab ID numbers.
If overnight - Frozen
>0.5 mL serum or plasma, paediatric minimum 0.25 ml
Ambient <8 hours, otherwise cold or frozen
Raised Values – exercise, stress (physical and psychological), sleep (stage IV), protein foods, arginine, hypoglycaemia, glucagon, L-Dopa, acromegaly, gigantism, some diabetics.
Low Values – (ie impaired response to stimulation tests) hypothyroidism, hypopituitarism, obesity, prepubertal status, bromocriptine, L-Dopa, somatostatin, glucose infusion.
GH reference range: (unstressed, no drugs):
Note: GH pulses may exceed reference values. The test is not suitable for samples obtained in pregnancy or under Pegvisomant treatment.
Adults: female <6 µg/L
male <0.6 µg/L
Children: A response to provocative testing of <3 µg/L is indicative of GH
$20.64 (Exclusive of GST)
Same day testing on request
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