Distinguishing Hypertension and Primary Aldosteronism Using Novel Immunoassay

A new chemiluminescent enzyme immunoassay (CLEIA) successfully detected hyperaldosteronism in patients with hypertension, according to a study published in Hypertension.

Researchers from Japan and the United States developed this immunoassay with the intention of reducing the time and cost of diagnosing primary aldosteronism, the most common cause of secondary hypertension. Approximately 10% of patients with hypertension and 20% of patients with resistant hypertension are estimated to have primary aldosteronism, but the exact number of cases is unknown, possibly because of the extensive workup required for screening and diagnosis.

A total of 222 patients with hypertension were referred for evaluation at a hospital in Japan, 125 of whom were diagnosed with primary aldosteronism. Of those patients, 75 had unilateral disease and were then diagnosed with aldosterone-producing adenoma, and 97 had essential hypertension.

The conventional radioimmunoassay showed that patients with either unilateral aldosterone-producing adenoma or bilateral hyperaldosteronism had higher plasma aldosterone concentrations, aldosterone-to-renin activity ratios, and captopril-challenged aldosterone-to-renin activity ratios vs patients with essential hypertension (P <.05). Meanwhile, there were no significant differences in baseline plasma renin activity

The novel active renin assay had a sensitivity of 0.1 pg/mL vs the radioimmunoassay sensitivity of 2.0 pg/mL, while the ratio of aldosterone-to-renin concentrations of 6.0 ng/dL per pg/mL had 92% sensitivity and 76.3% specificity as a cutoff for distinguishing primary aldosteronism from essential hypertension.

“This novel measurement is expected to be a clinically reliable alternative for conventional radioimmunoassay and to provide better throughput and cost effectiveness in diagnosis of hyperaldosteronism from larger numbers of [patients with hypertension] in clinical settings,” the researchers concluded.

Study Limitations

• Compared with the general hypertensive population, this study enrolled a disproportionate number of patients with primary aldosteronism
• Small, retrospective, single-center study

Reference

Morimoto R, Ono Y, Tezuka Y, et al. Rapid screening or primary aldosteronism by a novel chemiluminescent immunoassay [published online June 26, 2017]. Hypertension. doi:10.1161/HYPERTENSIONAHA.117.09078

This article originally appeared on The Cardiology Advisor