Oral Sodium Loading Test Is More Sensitive Than Seated Saline Infusion Test to Confirm Overt Primary Aldosteronism.

Context: Primary aldosteronism (PA), a frequent but underdiagnosed cause of hypertension, is associated with a significant burden of cardiovascular and renal complications. Studies have reported divergent results regarding the diagnostic performance of seated saline infusion test (SSIT) and oral sodium loading test (OSLT), 2 confirmatory tests recommended by the Endocrine Society Clinical Practice Guidelines. To our knowledge, no study directly compared the results of SSIT and OSLT to diagnose overt PA.

Objective: We assessed the diagnostic performance of SSIT and OSLT in a group of patients with hypertension and elevated screening aldosterone-renin ratio (ARR). The diagnostic standard was defined as hypertension with or without hypokalemia with an elevated screening ARR and at least 1 abnormal confirmation test including OSLT and SSIT.

Methods: A monocentric retrospective study was conducted, including 87 patients with hypertension with a positive screening who underwent both SSIT and OSLT. A diagnostic performance analysis was conducted using urinary aldosterone at a threshold of 27 nmol/day as the criterion for OSLT, in comparison to a plasma aldosterone concentration (PAC) exceeding 140 pmol/L following the saline infusion.

Results: A statistically significant difference in sensitivity was observed between OSLT and SSIT, with OSLT demonstrating superior performance ( = .025). The aforementioned test exhibited concordance in 59 cases (65.5%), indicating that these methods are not equivalent (McNemar test = .036).

Conclusion: OSLT demonstrated a significantly higher sensitivity for diagnosing overt PA in comparison with the SSIT in our cohort of patients with hypertension with an abnormal screening ARR.