September 24, 2017
Glucagon Test for Glycogen Storage Disorders Minimize

Glucagon test for glycogen storage disorders

Indication

This test is useful in the differential diagnosis of hypoglycaemia associated with ketosis.

Contra-indications

This test should not be performed if there is marked hypoglycaemia or lactic acidosis at the time of the test.

Principle

Glucagon produces a rise in plasma glucose by enhancing the catabolism of hepatic glycogen. Normal subjects will exhibit a rise in glucose but not in lactate unless there is a defect in gluconeogenesis.

Side effects

Some subjects will feel unwell and a proportion develop nausea and vomiting. Sweating, palpitations, and rarely, loss of consciousness and convulsions may occur due to severe hypoglycaemia.

Preparation

Prior to the test, measurement of glucose, U&Es for an assessment of anion gap should be measured.

Requirements

  1. 5 tubes for glucose and lactate (special tubes may be required for lactate measurements (contact the laboratory)
  2. Glucagon for im injection. Dose: 1 mg (adults), 20 microgram/kg (children)
  3. see protocol for emergency treatment of hypoglycaemia during ITT/glucagon test

Procedure

 

Site an indwelling cannula in the antecubital fossa with good access for administration of glucose, if required

time 0 min:

take 2 mL blood for glucose and lactate
immediately afterwards administer glucagon 20 microgram/kg i.m. (children)
For adults 1 mg i.m. should be administered

time 30 min:

take 2 mL blood for glucose and lactate

time 60 min:

take 2 mL blood for glucose and lactate

time 90 min:

take 2 mL blood for glucose and lactate

time 120 min:

take 2 mL blood for glucose and lactate

Interpretation

Adults: in normal subjects there is a rise in plasma glucose > 4 mmol/L. The larger tolerance in adults can be explained by the lesser disease severity in adults.

Children: in normal subjects there is a rise in plasma glucose > 2 mmol/L and a fasting or stimulated plasma lactate < 2.4 mmol/L.

GSD type

Glucose

Lactate

Effect of performing test post-prandially

type I

increased or
decreased

Normal or
increased

 

type Ib

reduced

increased

greater fall in glucose

type III

N

N

glycaemic response

type VI

increased

N

greater response

References

  • Pears JS, Jung RT, Hopwood D, Waddell ID, Burchell A. Glycogen storage disease diagnosed in adults. Quart J Med 1992;82:207-22.
  • Dunger DB, Leonard JV. Value of the glucagon test in screening for hepatic glycogen storage disease. Arch Dis Child 1982;57:384-9.
  

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