Reliability of a portable device for measuring spot urinary Na/K ratios among pregnant Thai women: a cross-sectional study

Abstract

Aim: Urinary Na/K ratios are related to the risk of developing cardiovascular diseases. A portable device which rapidly measures urinary Na/K ratios will be useful. This study aimed to test the reliability of a portable device for measuring spot urinary Na/K ratios among pregnant women in southern Thailand.

Methods: Morning spot urine samples were examined with a portable device and automated chemical analyzer independently and blindly. Correlations and predictions were analyzed using Spearman’s correlation coefficients and linear regression, respectively. Agreement between the portable device and automated chemical analyzer was examined using the Bland-Altman method.

Results: Measurements from 1,412 specimens revealed that spot urinary Na/K ratios obtained using the portable device had an acceptable level of agreement (mean of difference=0.78) and strong positive correlation (r=0.83) with those obtained using the automated chemical analyzer. The equation of urinary Na/K ratios obtained with the portable device is required to estimate ratios obtained by the automated chemical analyzer, which had a low proportional error and small constant error.

Conclusion: Portable devices are feasible alternative tools for measuring spot urinary Na/K ratios among pregnant women in clinical settings. Further large-scale studies to assess the reproducibility of measurements from portable devices are warranted.