Nocturia: when the heart wakes you up at night

BACKGROUND: Nocturia is a common and burdensome symptom that may reflect underlying cardiovascular dysfunction. While previous studies have linked nocturia to heart failure and fluid overload, direct hemodynamic evidence supporting this association remains limited. OBJECTIVE: To evaluate the relationship between left- and right-sided filling pressures, particularly pulmonary artery wedge pressure (PAWP) and right atrial (RA) pressure, and nocturia severity in a cohort of patients undergoing right heart catheterization. METHODS: We conducted a prospective observational study of 74 adult patients undergoing right heart catheterization with documented PAWP. Nocturia frequency was assessed via structured interview and modeled as an ordinal outcome. Spearman's correlation and ordinal logistic regression were used to examine associations between PAWP and nocturia severity. Additional analyses explored relationships with right-sided filling pressures (right atrial, right ventricular end-diastolic (RVEDP), and pulmonary artery (PA) pressures). Because of multicollinearity, we fit separate adjusted ordinal logistic models including one pressure variable at a time (PAWP, RA, PA and RVEDP), each adjusted for left ventricular ejection fraction (LVEF), diuretic use, and peripheral edema (where available). RESULTS: PAWP was significantly associated with nocturia severity (ρ = 0.35, p = 0.003). In adjusted ordinal logistic regression, each 1 mmHg increase in PAWP was associated with a 7-10% higher odds of more frequent nighttime voiding. In separate multivariable models adjusted for LVEF, diuretic use, and peripheral edema both RA pressure (OR 1.15 per mmHg, p = 0.021) and RVEDP (OR 1.17 per mmHg, p = 0.002) were independently associated with greater nocturia severity, wereas PA pressure showed a trend (OR = 1.06 per mmHg, p = 0.078). CONCLUSIONS: Both left- and right-sided ventricular filling pressures, particularly PAWP and RA pressure, are independently associated with nocturia severity in adjusted analyses. These findings support nocturia as a clinical marker of hemodynamic congestion, highlighting the importance of nocturia as a symptom of fluid overload and potential cardiac dysfunction.