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

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.

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.

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.

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.