Assessment of proteinuria by using the protein/creatinine ratio of single-voided urine.

Quantitative 24-hour urine protein excretion is used in the diagnosis, the monitoring of therapeutic effects and the prognosis of renal disease. However, this method is time-consuming, cumbersome and often inaccurate. Many studies have shown that the single voided urine protein/creatinine (Pr/Cr) ratio relates well with 24-hour urine protein excretion and can be substituted for evaluating some conditions. In our study, 41 patient with renal disease (25 men, 16 women) with a mean age of 43 years (range, 20-79 years), not only collected 24-hour urine, but also collected single voided urine at four different times. There was an excellent correlation between 24-hour urine protein excretion and the single voided urine Pr/Cr ratio at various degrees of creatinine clearance and ranges of proteinuria. The highest correlation was found in urine specimens collected at 16:00 hours with a correlation coefficient (r) of 0.91. Other urine specimens also showed a good relation with a correlation coefficient of above 0.80. The creatinine clearance (Ccr) greater than or equal to 70 ml/min group showed a better relationship than the Ccr less than 70 ml/min group. The proteinuria more than 1.0 g/day group also showed a better relationship than the group with proteinuria of less than 1.0 g/day. However, these differences were not statistically significant. No significant differences between the different age groups or sexes, using the single voided urine Pr/Cr ratio to estimate the 24-hour urine protein excretion were found. It is concluded that the single voided urine Pr/Cr ratio correlates highly with 24-hour urine protein excretion and could be an alternative means for disease monitoring and screening.