What is the role of plasma aldosterone/plasma renin activity ratio testing in the workup of primary aldosteronism?

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

Because the random plasma aldosterone/plasma renin activity (PRA) ratio is fairly constant over many physiologic conditions, it can be used for screening. Normal values are less than 270 when aldosterone concentration is expressed in pmol/L, or are less than 10 when aldosterone concentration is expressed in ng/dL. (See the chart below.) [24]

Algorithm for screening for potential primary aldo Algorithm for screening for potential primary aldosteronism.

When aldosterone is measured in ng/dL and PRA is measured in ng/mL/h, a plasma aldosterone/PRA ratio of greater than 20-25 has 95% sensitivity and 75% specificity for primary aldosteronism. When aldosterone is measured in pmol/L, a ratio greater than 900 is consistent with primary aldosteronism. [25, 26]


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