Objective:  We conducted a nationwide, population-based interaction analysis using body roundness index (BRI) and Kawasaki method for estimating 24-h urinary sodium excretion (e24hUNaEKawasaki, g/day) as candidate indicators. A total of 6,509 participants were all native South Koreans aged ≥ 20 years without significant medical illness. They were divided into quintiles according to their e24hUNaEKawasaki results and were subdivided by sex. Methods:  Participants in the highest e24hUNaEKawasaki quintile were more obese and had higher urine albumin:creatinine ratio. Multiple logistic regression, adjusted for various risk factors of CVD, demonstrated that both BRI (adjusted OR =1.413, 95% CI = 1.296-1.540) and e24hUNaEKawasaki (adjusted OR = 1.248, 95% CI = 1.119-1.391) were significantly associated with albuminuria. Our analysis revealed that high-sodium diet had a stronger effect on the risk of albuminuria in participants with central obesity than in those without (adjusted RERI = 0.901, 95% CI = 0.874-0.929; adjusted AP = 0.243, 95% CI = 0.047-0.439; adjusted SI = 1.498, 95% CI = 1.016-1.981). Results:  The results of our study demonstrate that both e24hUNaEKawasaki and BRI are candidate predictors of albuminuria and that the synergistic interaction of high sodium diet and central obesity may be associated with the development and progression of vascular endothelial dysfunction in the kidney. Conclusions: Objective:  Increased sodium intake or aberrant fat distribution is related to vascular endothelial dysfunction, which causes chronic cardiovascular disease. This study aimed to find the effect of possible interaction between a high-sodium diet and central obesity on albuminuria.  Methods:  We conducted a nationwide, population-based interaction analysis using body roundness index (BRI) and Kawasaki method for estimating 24-h urinary sodium excretion (e24hUNaEKawasaki, g/day) as candidate indicators. A total of 6,509 participants were all native South Koreans aged ≥ 20 years without significant medical illness. They were divided into quintiles according to their e24hUNaEKawasaki results and were subdivided by sex. Results:  Participants in the highest e24hUNaEKawasaki quintile were more obese and had higher urine albumin:creatinine ratio. Multiple logistic regression, adjusted for various risk factors of CVD, demonstrated that both BRI (adjusted OR =1.413, 95% CI = 1.296-1.540) and e24hUNaEKawasaki (adjusted OR = 1.248, 95% CI = 1.119-1.391) were significantly associated with albuminuria. Our analysis revealed that high-sodium diet had a stronger effect on the risk of albuminuria in participants with central obesity than in those without (adjusted RERI = 0.901, 95% CI = 0.874-0.929; adjusted AP = 0.243, 95% CI = 0.047-0.439; adjusted SI = 1.498, 95% CI = 1.016-1.981). Conclusions:  The results of our study demonstrate that both e24hUNaEKawasaki and BRI are candidate predictors of albuminuria and that the synergistic interaction of high sodium diet and central obesity may be associated with the development and progression of vascular endothelial dysfunction in the kidney.