Abnormal circadian pattern of urinary sodium excretion and chronic kidney disease progression

Background Abnormal circadian pattern of urinary sodium excretion was associated with high blood pressure and target-organ injury. However, whether urinary circadian pattern of sodium excretion is associated with chronic kidney disease (CKD) progression has not been elucidated. Methods We evaluated 1604 participants with CKD in this retrospective cohort study. We studied the association between clinical outcomes and day: night ratio of urinary sodium excretion, using urine collected separately during daytime and nighttime. The primary outcome was defined as a decrease of ≥ 30% in eGFR from baseline or initiation of renal-replacement therapy. The secondary outcome was a decrease of ≥ 50% in eGFR from baseline or initiation of renal-replacement therapy. Results The primary and secondary outcome occurred in 319 and 247 patients during 5710.2 person-years of follow-up, respectively. The Kaplan-Meier (KM) analysis showed an association between lower day: night ratio of urinary sodium excretion and primary and secondary outcome (both P < 0.05). In multivariate analysis, fully adjusted hazard ratios (95% confidence intervals) for patients with day: night ratio of urinary sodium excretion in the lowest quartile were 2.29 (1.55–3.39) for the primary outcome and 2.42 (1.53–3.85) for the secondary outcome, compared to the highest quartile. Conclusion Abnormal circadian pattern of urinary sodium excretion, characterized by a lower day: night ratio of urinary sodium excretion, is associated with CKD progression in CKD patients. These findings suggest day: night ratio of urinary sodium excretion may serve as a marker to recognize CKD progression. Clinical trial number Not applicable.