LAUSR

Objectives: To investigate the associations of metabolic syndromes (MS) and their components with estimated 24-hour urinary sodium excretion (24hUNaE) in Chinese adults. Methods: 40,693 participants aged 51.4 ± 9.7 years with the measurements of blood biochemistry, blood pressure and urinary sodium excretion at baseline from a prospective urban and rural epidemiology study in China (PURE-China) were selected for final analyses. MS were diagnosed based on the NCEP-ATP III criteria. 24hUNaE was estimated from the second fasting urine samples using the Kawasaki formula. Participants were divided into six categories per five cut-points of 24hUNaE levels as 2300, 3600, 4800, 6000, and 7200 mg/day. Multiple logistic regression analyses were used to investigate associations of MSs with 24hUNaE adjusted for possible covariates. Results: The prevalence of MS was 33.4%, and mean 24hUNaE was 5657.9 ± 1665.2 mg/day, equal to a sodium intake of 14.4 g/day. MS risk was significant at three highest categories of 24hUNaE in adjusted models compared with 2300–3599 mg/d of 24hUNaE (4800–5999 mg/d: odds ratio [OR], 1.18; 95% confidence interval [CI], 1.09–1.29; 6000–7199 mg/d: OR, 1.35; 95% CI, 1.23–1.47; > 7200 mg/d: OR, 1.41; 95% CI, 1.30–1.55). Positive associations of 24hUNaE with central obesity and reduced high density lipoprotein cholesterol were observed (p < 0.01 for trend), but inverse relationship with elevated fasting blood glucose was found (p = 0.002 for trend). A U-shape curve of 24hUNaE was shown relevant to elevated blood pressure (p < 0.01 for trend) and elevated triglyceride (p < 0.01 for trend). Conclusion: High sodium intake is likely to increase MS risk, especially for elevated blood pressure and central obesity. However, too low sodium intake might aggregate MS risk.