Dipstick urinary chloride as a surrogate marker of urinary sodium in cirrhosis: a prospective multicenter pilot study

BACKGROUND: Reduced urinary sodium excretion reflects disease severity in patients with cirrhosis, but routine use outside clinical settings is not feasible. Urinary chloride, reabsorbed alongside sodium, can be easily measured using a dipstick. This study examines the correlation between dipstick-measured urine chloride and urinary sodium/chloride concentrations and explores its potential to predict future acute decompensation (AD) in cirrhosis. METHODS: In this prospective multicenter pilot study, hospitalized patients with cirrhosis were enrolled from four Dutch hospitals. Single urine samples were collected for dipstick chloride measurement and laboratory analysis of urinary sodium/chloride. The primary outcome measure was the correlation between dipstick and lab-based urine electrolytes and the secondary outcome was the predictive value of dipstick chloride for new-onset AD development within 90-days. RESULTS: A total of 100 patients (62% male) were included, with a median age of 64 years [IQR 53-70]. Dipstick urinary chloride strongly correlated with laboratory urinary chloride (r=0.801) and urinary sodium concentrations (r=0.757). Within 90-days, the cumulative incidence of AD was higher in patients with low urinary chloride concentration (≤38 mmol/L) compared with those with high urinary chloride (44% vs 22%, p=0.014). Multivariate regression models showed that three variables were independently associated with an increased risk of developing new AD: low urinary chloride, diuretic use, and AD at inclusion. CONCLUSION: Dipstick-measured urinary chloride concentration correlates strongly with laboratory urinary sodium and -chloride concentration in patients with cirrhosis. Given its simplicity and low-cost, urine chloride dipstick testing may serve as a practical tool for monitoring disease course in clinical and outpatient settings.