Urine protein/creatinine ratio is a widely used initial method to estimate daily protein excretion in urine.^[1][2][3] Since the diagnosis and management of proteinuric renal diseases and the staging of chronic kidney disease depend on accurate identification and quantitation of proteinuria,^[4][1] the implementation of the 24-hour urine collection is the most accurate procedure in practice to figure out the urinary protein excretion.^[1] However, in current clinical practice, the urine protein/creatinine ratio is widely used to estimate daily protein excretion by virtue of its convenience and simplicity.^[5][1]

The difference between urine protein/creatinine ratio and 24-hour urine collection is that the former requires a urine sample to be collected only once at any time.^[6] [Creatinine(U)] is taken into account due to the notion that creatinine is normally released into the urine at a constant rate.^[6] Scientists found that the ratio of protein to creatinine roughly estimates the actual value gained from the 24-hour urine protein test.^[6] The normal urine protein/creatinine ratio is less than 200 mg/g.^[7]