Insulin hypoglycaemia stimulation test

Last updated: Wednesday, 17, March, 2004
Item Process
Specimen

5 mL blood in a lithium heparin or plain tube.

Method

Glucose - spectrophotometry.

Cortisol, growth hormone - immunoassay.

Protocol

After insertion of an intravenous line and collection of a baseline sample, a dose of 0.075-0.15 U/kg body weight of insulin is given intravenously.

5 mL blood in a lithium heparin or plain tube is collected at 30, 60 and 90 minutes for glucose, growth hormone and cortisol.

For the test to be valid glucose must fall to at least 2.2 mmol/L and/or hypoglycaemic symptoms must be present.

The test must be done in a hospital environment, a medical officer must be in attendance throughout the test and intravenous glucose must be available.

ApplicationInvestigation of suspected hypopituitarism. The test is contraindicated in patients with ischaemic heart disease, cerebrovascular disease or epilepsy.
InterpretationPituitary or hypothalamic hypofunction is indicated by a failure of cortisol to exceed 550 nmol/L and of growth hormone to exceed 10 µg/L.
ReferencePavord SR et al. Clin Endocrinol 1992; 36: 135-139.