Characteristics of Dietary Sodium Intake Assessed by 24-Hour Urine Collection in Korean Patients with Chronic Kidney Disease: Insights from the K-SALT Study

Objectives : Excess dietary sodium intake contributes to hypertension, volume overload, and kidney function decline in chronic kidney disease (CKD). Although sodium restriction is recommended, objective assessment remains still challenging in clinical practice.
Methods : We conducted the K-SALT study, a multicenter cohort of 1,640 adults with CKD from 16 Korean hospitals who completed a 24-hour urine collection between 2013 and 2025. Sodium intake was assessed using 24-hour urinary sodium excretion (24hrUNa). Associations with age, sex, body mass index (BMI), residential region, season, comorbidities, medication use, and estimated glomerular filtration rate (eGFR) were examined.
Results : Mean 24hrUNa was 149.7 ± 89.6 mmol/day and an estimated salt intake, 8.8 ± 5.2 g/day. Sodium excretion was correlated positively with eGFR (r=0.186, P < 0.001) and declined with advancing CKD stage. Male had higher sodium excretion than female, and 24hrUNa increased with increasing BMI (P < 0.001). In multivariable analysis, male, higher BMI, BMD, eGFR, and proteinuria were associated with higher 24hrUNa, whereas age, hypertension, and diabetes were not independently associated. Sodium excretion did not differ significantly by residential region or season. Use of loop diuretics, thiazides, and mineralocorticoid receptor antagonists was not independently associated with 24hrUNa, whereas sodium-glucose cotransporter 2 inhibitor use showed a modest association.
Conclusions : In the K-SALT study cohort, dietary sodium exposure measured by 24-hour urine collection remained above recommended targets and was more strongly associated with kidney function, sex, and BMI than with comorbidity status. Objective assessment using 24hrUNa may support individualized, stage-specific dietary counseling in patients with CKD.