Suppressed Renin Activity Outperforms Aldosterone-to-Renin Ratio in Identifying Primary Aldosteronism: Study

The findings, published in the Hypertension Journal, suggest that plasma renin activity alone may be a more sensitive approach for primary hyperaldosteronism screening than the aldosterone-to-renin ratio.

"In this retrospective study of 94,829 patients with suspected primary hyperaldosteronism, an ARR of 20 or higher identified 20.3% of patients with the condition. In contrast, a suppressed plasma renin activity of less than 1 ng/mL per minute was detected in 45.9% of patients with primary hyperaldosteronism," the researchers reported.

ARR, a widely used test, measures the ratio of aldosterone to renin in the blood. A high ARR suggests the presence of PA, prompting further diagnostic testing. Conversely, suppressed PRA refers to measuring low plasma renin levels in the context of high aldosterone levels, which can also indicate PA.

In many clinical settings, primary aldosteronism screening typically involves a single blood draw to measure plasma aldosterone concentration (PAC) and plasma renin activity, which is then used to calculate the aldosterone-to-renin ratio. However, ARR levels can vary between specialized centers and even with repeated tests in the same individual, highlighting the potential inconsistency of this screening method. As an alternative, a suppressed PRA, defined as less than 1 ng/mL per hour, has been proposed as a potential screening test.

Against the above background, Marco Marcelli, Quest Diagnostics Nichols Institute, San Juan Capistrano, CA, and colleagues aimed to compare two potential screening methods for identifying probable primary aldosteronism in a cohort of 94,829 paired PRA and plasma aldosterone concentration samples. The approaches evaluated were an ARR threshold of ≥30 or ≥20 versus a PRA suppressed to below 1 ng/mL per hour.

The study revealed the following findings:

• Of 94,829 patients, 20.3% tested positive based on ARR≥20, 13.9% based on ARR≥30, versus 45.9% based on suppressed PRA (<1 ng/mL per minute).
• In the PRA group, a range of aldosterone levels were observed: 5.5% had PAC >15 ng/dL, 25.2% had PAC 5 to 15 ng/dL, and 15.2% had PAC <5 ng/dL, compared with 6%, 12.7%, and 1.6% in the ARR≥20 group and 4.7%, 8.5%, and 0.7% in the ARR≥30 groups.

"In this cohort being screened for primary aldosteronism, significantly more individuals were identified using criteria based on suppressed renin activity compared to those identified with the aldosterone-to-renin ratio," the researchers concluded.

Reference:

Marcelli M, Bi C, Funder JW, McPhaul MJ. Comparing ARR Versus Suppressed PRA as Screening Tests for Primary Aldosteronism. Hypertension. 2024 Jul 23. doi: 10.1161/HYPERTENSIONAHA.124.22884. Epub ahead of print. PMID: 39041222.