Measurement of urinary sodium and potassium excretion with the proportional sampling device (Partition Cup) compared with the 24 hour whole urine collection

The role of sodium and potassium in hypertension has not been clarified, because studies made have used inadequate methods for the evaluation of electrolyte intake. The major methodological problem with electrolyte and hypertension is how to accurately estimate the electrolyte intake. The 24-hour urme collection method is commonly used for the measurement of electrolyte excretion, but it is very difficult to perform faithfully. Recently, various improved methods have been developed to evaluate the urinary electrolyte excretion ! the spot urine collection method, the filter paper method and the partition cup method (proportional sampling method). This study was designed to assess the utility of the partition cup method as compared with the 24-hour whole urine collection method. Seventy subjects (52 women and 18 men, 40-71 years old) collected the 24-hour urine used both the partition cup and the 24-hour whole urine collection device simultaneously. There were no remarkable differences in the urinary sodium and potassium concentration between the partition cup method and the 24-hour whole urine collection method. In urinary sodium and potassium excretion, marked differences between these two methods were obtained in onlv 13 of 70 subjects in sodium excretion and 15 of 70 subjects in potassium excretion because of variations in urinary volume. The use of the partition cup for epidemiological examination is practical and convenient and gives a good indication of electrolyte intake.