Validation of a Simple Device for Measuring Urinary Sodium-to-potassium Concentration Ratio

Abstract

The sodium-to-potassium concentration ratio (Na/K) in urine serves as a vital indicator for evaluating both dietary salt intake and the consumption of vegetables and fruits. Despite its significance, traditional methods for measuring the Na/K are often labor-intensive and cumbersome, making them impractical for routine daily use. To address this limitation, we developed a novel system named “P-Scan Na/K” designed for the quick and convenient measurement of the Na/K in urine. The system integrates a solid-state ion-selective electrode with a compact and portable measurement device, enabling users to easily assess Na/K in their urine samples. In measurements using actual urine samples, a high correlation was observed between the sodium ion and chloride ion concentrations measured by an automatic analyzer ([Na⁺] = 0.972[Cl⁻], R² = 0.976). Utilizing this relationship, the P-Scan Na/K calculated the urinary Na/K by using a chloride ion electrode as a counter electrode and measuring the potential of the sodium ion and potassium ion electrodes. As a result, the sodium-to-potassium ratio obtained with the P-Scan Na/K showed a good correlation with that measured by the automatic analyzer (linear regression for 97 samples: y = 1.218x - 0.464, R² = 0.736). This strong correlation suggests that the P-Scan Na/K system provides reliable data that can be used for health monitoring purposes. However, while the system shows great promise, certain challenges remain in enhancing its measurement precision. Addressing sensor variability, as well as minimizing fluctuations between different days and across various production batches, is crucial for ensuring consistent performance. These issues are particularly important for enabling the widespread adoption of the P-Scan Na/K system in everyday health management. In conclusion, the development of the P-Scan Na/K system represents a significant step forward in making the monitoring of dietary habits more accessible. With further refinements to improve accuracy and consistency, this system has the potential to become a valuable tool for individuals seeking to manage their health daily.