The effect of pH and urine dilution on the electrophoretic mobility of uric acid crystals.

As a result of a continuing programme to understand better the uric acid stone treatment and prophylaxis, an investigation of the effect of pH and urine dilution on the surface charge of uric acid crystals was undertaken. A microelectrophoretic technique was employed to characterize the nature of the surface charge and the electrokinetics of uric acid crystals both in natural and synthetic urines under different conditions of pH and dilution. Both dilution and alkalization reduced the specific conductance of urine and increased the electrophoretic mobility (zeta potential) of uric acid crystals. The presence of cationic additives in diluted urine altered the zeta potential of uric acid crystals. Such findings suggest that proper control of the pH level and urine dilution as well as the surface charge at the solid-liquid interface represent an important factor in the uric acid stone prophylaxis.