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HealthInfo Waitaha Canterbury

Dexamethasone suppression test

Whakamātaunga tāmi i te dexamethasone

The dexamethasone suppression test gives your doctor valuable information about your cortisol production. Cortisol is a hormone produced by your adrenal glands.


Contact the Endocrine Test Centre on (03) 364-0934 before you go for your dexamethasone suppression test. The Endocrine Test Centre is on the ground floor of the Christchurch Outpatients building, 2 Oxford Terrace.

  1. Take the two 0.5 mg dexamethasone tablets as a single dose, as prescribed by your general practice team or specialist, between 11 pm and midnight. Take the tablets with or after food.

    If you have diabetes, dexamethasone may increase your blood glucose (sugar) slightly for the next few days.

  2. Go to the Endocrine Tests Centre at 8 am the following morning for a blood test to assess your cortisol level.

    It's important that you go at 8 am, otherwise the test is not useful.

If you cannot go to the Endocrine Test Centre, arrange to have a blood sample taken at your local laboratory or general practice. It's still important that the blood sample is taken at 8 am.

Written by the Endocrine Department, Christchurch Hospital. Adapted by HealthInfo clinical advisers. Last reviewed June 2023.

Page reference: 211674

Review key: HIHOT-213639