Association between plasma aldosterone after saline infusion test and nocturnal hypertension in patients with suspected primary aldosteronism

BACKGROUND: Nocturnal hypertension (NH) is a significant risk factor for target organ damage and all-cause mortality. Post-saline infusion test plasma aldosterone concentration (post-SIT PAC) serves as an indicator of autonomous aldosterone secretion level, but its link to NH is uncertain. This study aims to explore the association between post-SIT PAC levels and NH in patients with suspected primary aldosteronism (PA). METHODS: Participants were classified into 3 groups after a saline infusion test (SIT): negative (post-SIT PAC < 5 ng/dL, n = 86), borderline (post-SIT PAC 5-10 ng/dL, n = 180), and positive (post-SIT PAC > 10 ng/dL, n = 75). Restricted cubic spline (RCS) plots were used to explore the dose-response relationship between post-SIT PAC and NH, while multivariable logistic regression models adjusted for potential confounders. RESULTS: In this retrospective study, the overall prevalence of NH was 70.4%. A positive, nonlinear association was identified between post-SIT PAC and NH (P-nonlinear