Background: Microalbumin/creatinine ratio (ACR) is an important index of renal and vascular function.
Methods: We related urine electrolyte excretion over a two hour period to ACR in 292 healthy adolescents aged 15 to 18ys following a controlled diet.
Results: Between hour 1 and 2, UNaV were not statistically different (p= 0.362), which established stability of the measurement. In contrast, UKV and Na+/K+ ratios both differed across time (p-value of < 0.001 for each). Mean values for ACR were 2.82, 2.77, and 2.91 (μg/mg) for overall, blacks, and whites; and the mean UNaV were 0.268, 0.273, and 0.2588 (meq/min). The Pearson correlation coefficients between UNaV and ln(ACR) for overall, blacks, and whites were -0.506, -0.472, and -0.592 (p-values of <0.001 for all). Linear fit lines were approximated at 95% confidence interval to show the relative changes in ln(ACR) with changes in UNaV. Overall, for every 0.1 UNaV (meq/min) increase, ln(ACR) decreases by 0.75, 0.63, and 0.87 for all, blacks, and whites respectively. Gender difference was also analyzed, but the difference between ln(ACR) and UNaV was not established.
Conclusion: UNaV is a reliable measurement in clinical practice, and it has shown a strong negative correlation with ln(ACR). The relationship shows that the impact of changes in UNaV on changes in ln(ACR) is less in blacks when compared to whites; which may suggest that ln(ACR) respond less sensitively to UNaV in blacks than whites. In addition to race differences, the ln(ACR) and UNaV relationship can be used as a primary predictive testing reference for the onset of potential kidney related diseases in adolescents with normal ACR values < 30 (μg/mg).