Simplified quantification of urinary protein excretion using a novel dipstick in children

Although the quantification of protein excretion is valuable for diagnosing and monitoring renal disease, accurate, timed, urine collection entails practical difficulties in children. Several authors have shown that the random urine protein/creatinine ratio (UP/UC) correlates well with timed protein excretion. A novel dipstick, Multistix PRO, has recently enabled us to analyze concentrations of both urinary protein and creatinine, semi-quantitatively, in 60 s. The aim of this study was to investigate whether the UP/UC values obtained by Multistix PRO correlate well with those obtained by quantitative methods and daily urinary protein excretion. In order to obtain the UP/UC values, we measured urinary protein and creatinine concentrations both semi-quantitatively by Multistix PRO and quantitatively by conventional methods. The relationship between the semi-quantitative UP/UC by Multistix PRO and the quantitative UP/UC by conventional methods was analyzed. Similarly, the relationship between the semi-quantitative UP/UC and daily urinary protein excretion was studied. Semi-quantitative UP/UC by Multistix PRO correlated closely with both quantitative UP/UC and daily urinary protein excretion (r=0.86 and r=0.91, respectively). A cut-off level of heavy proteinuria, i.e., nephrotic range of proteinuria (>3.5 g/day) corresponded to 3.0, assessed by UP/UC by Multistix PRO. The semi-quantitative UP/UC by Multistix PRO correlated well with both quantitative UP/UC and daily urinary protein excretion, and use of the Multistix PRO would avoid errors and difficulties associated with timed urine collection. It is, therefore, a useful tool to monitor the urinary protein excretion in children with renal diseases at outpatient clinic.