Clotted blood tube (Serum gel separator clot activator tube)

Minimum blood volume: 5 mL

Paediatric clotted blood tube

Number of vials: 2

Minimum blood volume: 1.6 mL

Reference range: < 8 µg/L (< 24 mIU/L)

(Source: from manufacturer's kit insert)

Treatment target: < 1 µg/L (< 3 mIU/L)
(Source: JCEM 2010; 95: 3141 - 8)

Conversion factor: µg/L x 3 = mIU/L

Footnote:
GH is released in a pulsatile manner, usually < 8 µg/L (< 24 mIU/L). For patients receiving somatostatin receptor ligand therapy, the treatment target would be < 1 µg/L (< 3 mIU/L).

Investigations of pituitary and hypothalamic disorders causing growth abnormalities

Secretion of growth hormone by pituitary gland is episodic and pulsatile, therefore growth hormone as an isolated test is of limited value as levels fluctuate considerably in normal individuals. Dynamic tests are required for proper diagnosis. (See extended oral glucose tolerance test and IGF-1 for GH excess; glucagon stimulation test, clonidine stimulation test and insulin stimulation test for GH deficiency).

Low levels which are not able to be stimulated to a level achieved by normal subjects occur in pituitary dwarfism in children.

High or normal levels which cannot be suppressed are found in gigantism and acromegaly.