Metyrapone suppression test
To establish the correct functioning of the ACTH axis in suspected secondary hypocortisolism, where Insulin tolerance or glucagon stress tests are contraindicated.
As an alternative to the Short Synacthen Test for evaluation of primary hypocortisolism.
Previous adverse reaction to metyrapone.
Most commonly nausea and perhaps vomiting with the medication (reduced by taking metyrapone with a snack).
Headaches, dizziness and sedation, allergic skin reactions.
PREPARATIONStop all oestrogen therapy 6 weeks prior to test.
No need to fast.
Red top Vacutainer (plain clotted) x 1, Purple top Vacutainer (EDTA) x 1.
Vacutainer adaptor for cannula.
Admit to hospital for a night’s stay.
Calculate dose of metyrapone (30 mg/kg):
Body weight Dose of metyrapone
<70 kg 2.0 g
70-90 kg 2.5 g
>90 kg 3.0 g
Administer calculated dose of metyrapone at midnight with a snack (e.g. milk and biscuits).
At 0800h-0900h the following morning, sample for ACTH, 11-deoxycortisol, cortisol.
After blood sample, administer hydrocortisone 10 mg PO to cover for hypocortisolism.
Patient can be discharged home after hydrocortisone given.
SENSITIVITY AND SPECIFICITY
The performance of the Metyrapone test has been compared to the ITT as a gold standard in various studies. Using the criteria as above (Courtney 2000) the specificity is 77% and sensitivity 86%.
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Courtney CH, McAllister AS, McCance DR, Hadden DR, Leslie H, Sheridan B,
Atkinson AB. Clin Endocrinol (Oxf). 2000 Sep;53(3):309-12.
Gibney J, Healy ML, Smith TP, McKenna TJ. J Clin Endocrinol Metab. 2008 Oct;93(10):3763-8.