Feasibility of Assessment of Habitual Salt Intake Using a 24-h Urinary Salt Excretion Self-Measuring Device

To assess habitual salt intake, tools are needed to measure 24-h urinary salt excretion repeatedly. We developed and validated a new portable salt monitor, which measures salt excreted per urination and sums the values to provide an accurate estimate of urinary salt excretion over 24 h.

A previously developed salt monitor was improved with respect to the capacity, volume sensors, and equation for urinary sodium chloride concentration estimation. In 20 healthy Japanese female volunteers, 24-h urinary salt excretion was measured using the salt monitor and a conventional 24-h urine collection method on eight nonconsecutive days.

In a total of 157 days, there were no fixed or proportional errors between the methods. The mean salt intake over 8 days was 8.5 ± 2.0 g/day for the 24-h urine collection and 8.3 ± 2.3 g/day for the salt monitor, showing a strong correlation (r = 0.912, p < 0.001). At a cut-off value of 6 g, the salt monitor was able to completely classify individuals by habitual salt intake.

The validity of the new salt monitor was confirmed. The device can be considered an alternative to the traditional 24-h urine collection for repeated surveys and self-management of daily salt intake.