Laboratory: Clinical Biochemistry  (SPECIAL CHEMISTRY)
Test Name:
GLUCAGON STIMULATION TEST - (S)
Test Code: GLGN
Clinical Information:
Description: This provocative test may be used to assess growth hormone secretion capacity in patients suspected of GH deficiency:

· Those with signs and symptoms of hypothalamic-pituitary disease

· Those who have received cranial radiation or tumor resection

· Those with traumatic brain injury or sub-arachnoid hemorrhage

 

This procedure is performed in the Endocrinology & Metabolism Clinical Investigation Unit for adult patients.
Collection Devices:
Serum tubes with no gel are also acceptable.
Specimen Required:


Serum: 1.0 mL
Pediatric Serum: 0.4 mL

Follow lab instruction on the Glucagon Stimulation Requisition Form.
Referral:
Requisition:
Reference Values:
Reference Intervals: 
AgeInterpretation
<19 yPeak growth hormone (GH) <5 ug/L is consistent with severe GH deficiency. Some experts consider peak response 5-10 ug/L as equivocal. BMI-adjusted thresholds must be used in transition patients when appropriate.
≥ 19 yBMI-adjusted thresholds 1-3 ug/L combined with pretest probability must be used as appropriate. (Molitch ME et al., J.Clin.Endocrinol.Metab (2011):96(6):1587-609). 


Growth hormone stimulation test cut-off values are assay dependent and somewhat arbitrary. An inadequate response to at least two stimulation tests, along with auxologic data and clinical assessment consistent with growth hormone deficiency are required to confirm a diagnosis.
 

Some laboratories recommend a peak value of > 10 ug/L for pediatric patients and suggest values of 5 – 10 ug/L are indeterminate. Values < 5 ug/L are generally considered subnormal.

 
Availability:
Endocrinology Consult Required
See Also:
More Information:
Follow lab instructions given on the Glucagon Stimulation Requisition Form.