24-hour urine protein quantification is the gold standard for detecting total urinary protein but is cumbersome, time-consuming, and prone to contamination. To find a testing method that can replace 24-hour urine protein quantification and both indicate the severity of proteinuria and be convenient for patients, the K/DOQI guidelines summarized decades of research and concluded that the urine albumin-to-creatinine ratio (ACR) can accurately assess the rate of protein excretion in urine. It only requires a single random urine sample (preferably morning urine) for testing and is not affected by hydration status. This ratio reduces the impact of urine volume variation on random urine albumin concentration and is more convenient than timed urine collection for quantitative measurement.