Lab Information Manual

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.

Clinical Practice Change - Endocrine Testing and Specialized Endocrinology Requisition Update 15-May-24

Collection Devices:

Preferred Device:	1 - Serum Separator (SST) Tube(s) - Full Tube Collection Serum Separator (SST) Tube(s) - Full Tube Collection Manufacturer: Becton Dickinson Catalogue #: 367986
Alternate Device:	2 - Microtainer(s) - Serum Separator (0.6mL) Microtainer(s) - Serum Separator (0.6mL) Manufacturer: Becton Dickinson & Company Catalogue #: 365967

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:

Glucagon Stimulation

Reference Values:

Reference Intervals:

Age	Interpretation
<19 y	Peak 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 y	BMI-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