Association of the Estimated 24-H Urinary Sodium Excretion with Albuminuria in Adult Koreans: The 2011 Korea National Health and Nutrition Examination Survey

BACKGROUND Sodium intake and albuminuria have important roles in blood pressure and renal progression. Although their relationship has been reported, the results have not been consistent and all studies have examined small populations. OBJECTIVE This study investigated the role of the estimated 24-h urinary sodium excretion as a marker of sodium intake and albuminuria. DESIGN This investigation included 5,187 individuals age 19 years and older from a cross-sectional, nationally representative, stratified survey: The Korea National Health and Nutrition Examination Survey (KNHANES V-2), in 2011. Albuminuria was defined as a urinary albumin/creatinine ratio ≥30 mg/g. The 24-h urinary sodium excretion was estimated from a spot urine. RESULTS On classifying our participants into quartiles based on the estimated 24-h urinary sodium excretion, the prevalence of albuminuria increased with the 24-h urinary sodium excretion (5.3, 5.7, 7.5, and 11.8% in the first through fourth quartiles, respectively, p for trend <0.001). Even after adjusting for age, sex, diabetes, obesity, and hypertension, the significance persisted. In a multiple logistic regression analysis, the second and third quartiles of the estimated 24-h urinary sodium excretion were not associated with the presence of albuminuria with the first quartile as a control. However, the fourth quartile was significantly associated with the presence of albuminuria (odds ratio 1.61 [95% confidence interval 1.71-2.21], p = 0.003) after adjusting for age, sex, diabetes, obesity, and hypertension. CONCLUSIONS These findings suggest that salt intake is associated with the presence of albuminuria in the general Korean adult population.