Specimen Collection

Sample stability:

• 8 hours at 20-25 ^o C
• 1 day at 2-8 ^o C
• 1 month at -20 ^o C

4.5 mL Adult PST Blood (Preferred)

0.5 mL Paediatric Micro-PST Blood (Preferred)

5 mL Adult Heparin Blood

4 mL Plain Blood

3.5 mL SST Blood

0.5 mL Paediatric Microsample Blood

0.5 mL Paediatric Micro-heparin Blood
Reference Intervals

The reference interval for random GH samples cannot be clearly defined as GH is secreted in a pulsatile fashion and may vary from 0 - 24 ug/L.

Crossreaction with Pegvisomant

Pegvisomant is a modified GH molecule with GH antagonist properties. Most GH assays crossreact with pegvisomant: falsely high or falsely low results may occur depending on the assay (ref.1).

Uncertainty of Measurement: 4%

Conversion factor: ug/L x 3.0 = mIU/L

Turnaround Time: Within 3 hours
Assay Method

Principle: Sandwich type immunoassay with chemiluminescence detection

Assay: Roche Elecsys hGH

Analyser: Cobas e801

Diagnostic Use and Interpretation

GH excess

GH is increased in pituitary gigantism and acromegaly. In suspected acromegaly, a random GH and IGF-1 are the initial investigations. A GH of less than 0.25 ug/L excludes acromegaly.

In suspected acromegaly, the finding of a high random GH needs to be confirmed with a glucose GH suppression test. A nadir GH of <0.4 ug/L in the test is indicative of absence of disease or remission, while a GH level > 0.4 ug/L indicates acromegaly (ref. 2) .

GH deficiency

A random GH sample cannot be used to diagnose GH deficiency; a stimulation test is required.

In stimulation tests, a peak GH level >5 ug/L is generally regarded as normal, and a value <3 ug/L suggests GH deficiency. Values between 3 and 5 ug/L suggest partial GH deficiency.

• Suppression or stimulation tests may be arranged with the Dept. of Endocrinology.

Also see hypoglycaemia - investigations

References

1. Bidlingmaier M, Freda PU. Measurement of human growth hormone by immunoassays: current status, unsolved problems and clinical consequences. Growth Horm IGF Res 2009;20:19-25

2. Giustina A, Chanson P, Bronstein MD, et al. A consensus on criteria for cure of acromegaly. J Clin Endocrinol Metab 2010;95:3141-8.

Contact Information

Emails to chemicalpathologist@adhb.govt.nz will receive priority attention from the on-call chemical pathologist.

If the query concerns a specific patient please include the NHI number in your email.

If email is not a suitable option, please contact the on-call chemical pathologist via Lablink (Auckland City Hospital ext. 22000 or 09-3078995).

Individual chemical pathologists may be contacted but will not be available at all times.

After-hours : contact Lablink (Auckland City Hospital ext. 22000 or 09-3078995) or hospital operator for on duty staff after hours.

Dr Samarina Musaad (Clinical Lead) : SamarinaM@adhb.govt.nz ext. 22402

Dr Cam Kyle: CampbellK@adhb.govt.nz ext 22052

Dr Weldon Chiu: WeldonC@adhb.govt.nz ext. 23427

Dr Campbell Heron: CHeron@adhb.govt.nz ext. 23427

Dr Sakunthala Jayasinghe: Sakunthala@adhb.govt.nz ext. 23427

Specimen Transport Instructions for Referring Laboratories

Send a separated frozen aliquot, or at least 300 uL serum aliquot. Transport frozen.

Last updated at 15:26:00 06/01/2025