Nocturia is a common condition in aging populations and increasingly recognized as a systemic health indicator. While previous research suggests an association between nocturia and mortality, the mechanisms underlying this link remain poorly defined. This study investigated whether elevated serum uric acid (SUA) and metabolic syndrome (MetS) mediate the relationship between nocturia and all-cause mortality.

Data were obtained from the U.S. National Health and Nutrition Examination Survey (NHANES 2005–2014), linked to mortality outcomes through 2019. Adults aged ≥40 years with available data on nocturia, SUA, and MetS were included. Nocturia was defined as ≥2 voids per night. MetS was diagnosed using standard criteria requiring ≥3 out of 5 risk factors. Propensity score matching (1:1) controlled for age, sex, and race/ethnicity, resulting in 4,632 matched pairs. Cox proportional hazards models and mediation analyses were used to assess the relationships between nocturia, mortality, and mediating variables.

Nocturia was associated with a higher mortality risk (hazard ratio [HR] 1.28; 95% confidence interval [CI] 1.17–1.40; p<0.001). Participants with nocturia also had higher SUA and a greater prevalence of MetS. Mediation analysis revealed that both SUA and MetS partially explained the association between nocturia and mortality (indirect HR for SUA: 1.02; MetS: 1.003; all p<0.05). However, nocturia remained an independent predictor of mortality even after adjustment.

Nocturia is significantly associated with increased all-cause mortality, and this relationship is partially mediated by elevated serum uric acid and metabolic syndrome. These findings suggest nocturia may serve as a marker of systemic dysfunction. Early evaluation and management of metabolic abnormalities and uric acid levels may improve long-term outcomes in patients with nocturia.