[Quantification of proteinuria by measurement of the protein/creatinine ratio]

Accurate quantification of urinary protein excretion is difficult due to problems in 24-hour urine collection. We have evaluated the value of the protein/creatinine ratio in one single urine sample. There was an excellent correlation between this ratio and the protein content of a 24-hour urine collection [Pu (g/24 h) = 11.7 Pu (g/l) Cr (mmol/l); r = 0.96; P less than 0.001]. The best correlation was found with the sample collected after the first voided morning specimen. In our experience the ratio is more accurate for the quantification of urinary protein excretion than measurement of protein excretion in the same urine sample and also determination of protein excretion in 24-hour urine collected under the usual ambulatory conditions. We suggest that the protein/creatinine ratio should be used in ambulatory and hospitalized patients, especially for multicentric clinical trials in nephrology.