THIS TEST IS POTENTIALLY DANGEROUS.
A DOCTOR MUST ATTEND THE PATIENT THROUGHOUT

Indication

To test the hypothalamic/pituitary/adrenal axis. A normal short synacthen test renders the test unnecessary. To assess GH reserve.

Contraindications

Patients with ischaemic heart disease, history of seizures, craniotomy, those over 70 years old, those with a 0900h cortisol of <100nmol/L and untreated hypothyroidism.

Procedure

The patient should be fasted overnight and must be monitored for hypoglycaemia throughout the test.

1. Insert an indwelling intravenous cannula.
2. Wait 30 minutes.
3. Take blood for basal glucose (grey top vial), cortisol and growth hormone (red vial).
4. Inject human soluble insulin intravenously. See below for dosage.
5. Take blood at 30, 45, 60, 90 and 120 minutes for glucose, cortisol and growth hormone as appropriate.

Glucose for intravenous administration should be available in case of severe hypoglycaemia; the test however should not be aborted, as the stress is obviously adequate.

At the conclusion of the test the patient should be given lunch and a sweet drink. Observe for 2 hours and ensure that capillary blood glucose is normal.

Insulin dose

	Children	Adults
Usual	0.1U/kg	0.15U/kg
Probable hypopituitarism	0.05U/kg	0.1U/kg
Obese, Cushing's, Acromegaly	0.1U/kg	0.3U/kg

Interpretation guidelines

Plasma glucose should fall below 2.2mmol/L.

Serum cortisol should rise to at least 550nmol/L.

Peak serum GH level should exceed 20mU/L, responses between 10 and 20mU/L are equivocal.