Impact of Dietary Sodium and Protein Restriction adherence on change in Blood Pressure, estimated Glomerular filtration rate, Urinary Urea Nitrogen and Urinary Sodium in CKD stages 3 to 5 non Dialysis patients

Background : This study addresses the gap of long-term adherence to dietary protein and sodium restrictions by measuring urinary urea nitrogen (UUN) and urinary sodium excretion across dietary protein intervention groups. Further, assessing how varying protein intake and salt affects dietary compliance over time and its impact on blood pressure. Methodology : This two-year prospective RCT included CKD stages 3 to 5 (non-dialysis) patients aged 18 to 60 years. Participants were randomized into three groups based on protein intake: Normal Protein (NP- 0.8–1.0 g/kg/day), Low Protein (LP- 0.6 g/kg/day), and Very Low Protein (VLP- 0.3 g/kg/day, supplemented with keto-analogues). Dietary intake was analyzed using DietCal. Protein and sodium intakes calculated using UUN and Kawasaki method, respectively. Six monthly Repeated-Measures ANOVA was evaluated for dietary adherence trends and their association with BP and eGFR. Results : Of 100 enrolled participants, fifty percent where males, age 41.1 ± 8.5 years; BMI 23.9 ± 4.8 kg/m². Both urinary sodium and UUN levels significantly declined in LP and VLP groups, reflecting protein restriction adherence (p<0.05), without any change in NP group. Dietary sodium and urinary sodium showed strongest correlation in NP (r=0.58), moderate in LP (r=0.44), and weakest in VLP (r=0.28). Protein intake and UUN correlated significantly only in LP (r=0.33; p=0.005). Whereas, BP decreased non significantly. LP and VLP groups showed slower eGFR decline, suggesting possible renal protection. Conclusion : Urinary biomarkers (UUN and sodium) effectively reflect dietary adherence in CKD patients. Low protein and sodium intake significantly correlated with better renal function and blood pressure.