How is the dexamethasone suppression test used to diagnose primary aldosteronism?

Updated: Mar 24, 2020
  • Author: Gabriel I Uwaifo, MD; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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Answer

In the subset of primary aldosteronism patients with glucocorticoid-remediable aldosteronism (GRA), small doses of dexamethasone (1-2 mg/day) induce full normalization in plasma and urinary aldosterone levels. This is invariably associated with improvement in hypertension (HTN) in these patients. Other reports suggest a cut-off level for plasma aldosterone of less than 4 ng/dL and/or a relative plasma aldosterone suppression of greater than 80% of the baseline for the diagnosis of GRA following the dexamethasone challenge.

Three variants of familial primary aldosteronism exist. Type 1 familial primary aldosteronism (also called GRA) is associated with improvement in HTN using low-dose dexamethasone. Types 2 and 3 familial primary aldosteronism are not dexamethasone suppressible.


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