The potential of at-home prediction of the formation of urolithiasis by simple multi-frequency electrical conductivity of the urine and the comparison of its performance with urine ion-related indices, color and specific gravity

Abstract

It is important to control daily diet, water intake and life style as well as monitor the quality of urine for urolithiasis prevention. For decades, many ion-related indices have been developed for predicting the formation of urinary stones or urolithiasis, such as EQUILs, relative supersaturation (RSS), Tiselius indices (TI), Robertson risk factor algorithms (RRFA) and more recently, the Bonn risk index. However, they mostly demand robust laboratory analysis, are work-intensive, and even require complex computational programs to get the concentration patterns of several urine analytes. A simple and fast platform for measuring multi-frequency electrical conductivity (MFEC) of morning spot urine (random urine) to predict the onset of urolithiasis was implemented in this study. The performance thereof was compared to ion-related indices, urine color and specific gravity. The concentrations of relevant ions, color, specific gravity (SG) and MFEC (MFEC tested at 1, 10, 100, 5001 KHz and 1 MHz) of 80 random urine samples were examined after collection. Then, the urine samples were stored at 4 °C for 24 h to determine whether sedimentation would occur or not. Ion-activity product index of calcium oxalate (AP(CaOx) EQ2) was calculated. The correlation between AP(CaOx) EQ2, urine color, SG and MFEC were analyzed. AP(CaOx) EQ2, urine color and MFEC (at 5 frequencies) all demonstrated good prediction (p = 0.01, 0.01, 0.01, respectively) for stone formation. The positive correlation between AP(CaOx) EQ2 and MFEC is also significant (p = 0.01). MFEC provides a good metric for predicting the onset of urolithiasis, which is comparable to conventional ion-related indices and urine color. This technology can be implemented with much ease for objectively monitoring the quality of urine at points-of-care or at home.

Urine and stone analysis for the investigation of the renal stone former: a consensus conference

“…Increasing urine volume is a common form of treatment for stone patients, and a simple qualitative monitoring of urine colour [91] or urine conductivity [92] have been reported as being useful to patients who are seeking to maintain an appropriate intake of fluids. For some kinds of stones, the value of the urine pH is an important indicator of treatment success [93] and tracking this through each day using a dipstick has been recommended for cystinuric patients [1].…”

Development of a Portable Multi-Sensor Urine Test and Data Collection Platform for Risk Assessment of Kidney Stone Formation

“…The system measured four parameters-pH, Ca 2+ , uric acid concentration and conductivity-of the sample from the first void urine in the morning, based on the method performed in [11]. By taking the first void urine in the morning, we could further assess the possibility of stone formation, because such urine has stayed for a relatively longer time in the urinary tract.…”

“…In the previous approaches of system implementation, the on-board module was designed for single-parameter measurement. Figure 1 shows the on-board implementation from [11], used for the measurement of urine sample conductivity.…”

“…In the previous approaches of system implementation, the on-board module was designed for single-parameter measurement. Figure 1 shows the on-board implementation from [11], used for the measurement of urine sample conductivity. The on-board implementation of the potentiometric circuit presented in [18] was used for measuring the pH and Ca 2+ in urine samples, as shown in Figure 2.…”

Markers of lithogenic activity in kidney stone disease

“…Электропроводность мочи, измеренная при разных частотах пропускаемого тока, изучалась A.A. Silverio и соавт. Авторы считают, что их тест «продемонстрировал хорошую способность предсказывать развитие нефролитиаза, сравнимую с индексами, рассчитанными на основании содержания ионов в моче» [44].…”