Strategy to Control Catheter Encrustation With Citrated Drinks: A Randomized Crossover Study

Purpose

Nucleation pH is the pH at which Ca and Mg come out of urine to form crystals. If the safety margin between voiding pH and nucleation pH could be increased, it would increase the possibility of an alternative to controlling the activity of urease producing bacteria as a strategy to control catheter encrustation.

Materials and Methods

We performed a 6-week randomized crossover study in 24 patients with catheter blockage who were randomly allocated to a specific sequence of 3 consecutive available treatments, including increased fluid intake, lemon juice and potassium citrate. Each patient received all available regimens. At the end of each week 24-hour urine samples were analyzed for voiding and nucleation pH, citrate, Ca and Mg.

Results

Mean ± SD nucleation pH increased from 7.45 ± 0.60 at baseline to 7.93 ± 0.50, 7.68 ± 0.64 and 7.96 ± 0.37 in the lemon juice, increased fluid intake and potassium citrate groups, respectively (p <0.0001). Mean urinary citrate increased significantly (p <0.0001), in particular due to lemon juice and potassium citrate effects. The association between treatment and Ca was weak (p = 0.12) while that of Mg was negative due to lemon (p <0.001). Average increase in the safety margin (nucleation pH minus voiding pH) beyond baseline was 0.84 (95% CI 0.63–1.04), 0.57 (95% CI 0.37–0.78) and 0.41 (95% CI 0.20–0.61) for lemon juice, increased fluid intake and potassium citrate, respectively. A strong treatment effect on the safety margin was apparent even when controlling for study design (p <0.001).

Conclusions

Increased fluid intake with lemon juice may be a simple, inexpensive, effective strategy to control catheter encrustation.

Key Words: urethra, urinary catheterization, hydrogen-ion concentration, potassium citrate, Proteus mirabilis

Abbreviations and Acronyms: pH_n, nucleation pH, pH_v, voided urine pH