What is the role of serum aldosterone testing to confirm primary aldosteronism?

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

After 3 days of an unrestricted sodium diet and 1 hour of full recumbency, healthy individuals have aldosterone levels of less than 15 ng/dL. When serum aldosterone is elevated above 22 ng/dL and renin is suppressed, the serum aldosterone (S-Aldo) test virtually confirms the diagnosis of primary aldosteronism. However, because aldosterone secretion is variable, the negative and positive predictive value of a single random aldosterone level is limited.

As many as 40% of patients with primary aldosteronism have serum aldosterone levels that remain within the reference range on repeated testing, as is typically the case in essential hypertension (HTN). (See the chart below.)

Algorithm for confirmation of primary aldosteronis Algorithm for confirmation of primary aldosteronism.

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