Dexamethasone Suppression Test

Dexamethasone Suppression Test
Tube Type
Serum (Gold Top)
Clinical Indication
Investigation of Cushing’s syndrome or Hyperadrenalism – excess cortisol production.
Dexamethasone suppresses cortisol – a raised result is likely due to increased cortisol or ACTH production
Target turnaround time
1 working day
Special requirements & notes
Indicate Dexamethasone Suppression Test is being undertaken on the order/form – laboratory comments relating to the analysis will be appended
1mg dose of dexamethasone (oral) given between 21:00 and 23:00hr (15ug/kg bodyweight in children).
Blood sample taken for analysis between 08:00 and 10:00 the following morning.
Clinical Report
Cortisol reported. If a cortisol result is suppressed (<50nmol/L), a diagnosis of Cushing’s is unlikely.
If further confirmation is required, suggest 24hour urine cortisol analysis (Link to specimen container information)
Volume required
1 tube (4ml)
If delayed transport to lab, store:
Centrifuged, in refrigerator
Factors affecting result interpretation
If patients are on anticonvulsants, consider increased dose – induce metabolism of the dexamethasone
Pathology discipline
‘Lab Tests Online’ link
Click here
Posted in Assay.

Last updated: July 23, 2019