Equis ISSN 2398-2977

Endocrine: dexamethasone suppression test

Synonym(s): Dex. suppression test, dxm suppression test, DST

Contributor(s): Kathleen P Freeman, Ramiro Toribio, Han van der Kolk, David Rendle

Overview

  • Dynamic response of adrenal gland with suppression of cortisol levels due to dexamethasone Dexamethasone administration.

Sampling

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Tests

Methodologies

  • Radioimmunoassy.
  • Chemiluminescence.
  • Method determines required specimen types (plasma or serum).

Availability

  • Most veterinary commercial, reference or university laboratories.

Validity

Sensitivity

  • 65% (non-Fall).

Specificity

  • 90% (non-Fall).

Technique (intrinsic) limitations

  • Some overlap of values with responses obtained in normal horses.
  • Resting cortisol (pre-ACTH) may be low, within normal limits or elevated.
  • Both false negative and false positive tests occur.

Technician (extrinsic) limitations

  • Requires interpretation in conjunction with clinical signs and results of other testing.

Result Data

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Borer-Weir K E et al (2013) Seasonal and annual influence on insulin and cortisol results from overnight dexamethasone suppression tests in normal ponies and ponies predisposed to laminitis. Equine Vet J 45 (6), 688-693 PubMed.
  • Donaldson M T et al (2005) Variation in plasma adrenocorticotropic hormone concentration and dexamethasone suppression test results with season, age and sex in healthy ponies and horses. J Vet Intern Med 19 (2), 217-222 PubMed.
  • Eiler H et al (1997) Results of a combined dexamethasone suppression/thyrotropin-releasing hormone stimulation test in healthy horses and horses suspected to have a pars intermedia pituitary adenoma. JAVMA 211, 79-81 (for description of methodology and value in diagnosis of pituitary adenoma) PubMed.


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