Clinical Information

The combined aldosterone/renin tests are preferred when screening for hyperaldosteronism. When prorenin, the inactive precursor of renin, is cryoactivated to renin during sample handling, falsely elevated results are obtained. Cryoactivation occurs when patient samples are chilled to temperatures of 4°C or below for extended periods of time, and when samples are chilled but still liquid (i.e., not frozen). Cryoactivation of prorenin to renin occurs more rapidly in serum. Prorenin blood concentration is approximately ten-fold greater than that of renin.

Based on 2025 Endocrine Society guidelines, screening for primary aldosteronism may be considered positive when:

1. Renin is suppressed (direct renin concentration is less than or equal to 5.2 pg/mL) AND
2. Plasma aldosterone concentration is greater than or equal to 10 ng/dL AND
3. Aldosterone-renin ratio is >4.0

Notes: A suppressed renin (less than or equal to 5.2 pg/mL) with aldosterone 10-20 ng/dL may still be consistent with primary aldosteronism, even if the aldosterone-renin ratio is less than or equal to 4.0. Repeat testing in the morning may be needed.