Clinical and Biochemical Features Associated with Coexisting Primary Aldosteronism in Patients with Obstructive Sleep Apnea: A Cross-Sectional Study

Background: Obstructive sleep apnea (OSA) and primary aldosteronism (PA) are linked by bidirectional mechanisms. Although guidelines recommend PA screening in hypertensive patients with OSA, simple tools for clinical prioritization remain limited. We aimed to characterize clinical, polysomnographic, and biochemical features associated with coexisting PA in patients with OSA. Methods: We conducted a cross-sectional study in 107 adults with OSA and definitive PA classification, including 30 patients in the OSA+PA group and 77 in the OSA-only group. Clinical, polysomnographic, and fasting biochemical variables were collected using standardized procedures. Multivariable logistic regression was used to examine factors associated with coexisting PA. Results: Compared with the OSA-only group, the OSA+PA group had a larger neck circumference (42.0 ± 4.6 vs. 39.8 ± 3.7 cm, p = 0.010), a higher snoring index (369.9 ± 320.3 vs. 252.0 ± 264.9, p = 0.040), and higher aldosterone levels (25.8 ± 18.8 vs. 10.7 ± 7.3 ng/dL, p = 0.001), while glycated hemoglobin was lower (6.4 ± 1.6 vs. 7.5 ± 2.1, p = 0.005) and serum potassium was significantly reduced (3.5 ± 0.4 vs. 4.0 ± 0.4 mmol/L, p = 0.001). In multivariable analysis, aldosterone (OR = 1.138, p = 0.001) and serum potassium (OR = 0.017, p = 0.001) were associated with coexisting PA. Conclusions: Higher aldosterone and lower serum potassium were readily available biochemical features associated with coexisting PA among clinically selected patients with OSA.