Urinary protein or albumin/creatinin ratio for reporting measurements results

Urinary proteins or urinary albumin exhibit a high intra individual variability. Therefore, urine collected during 24 hours has been recognized as a reference biological fluid for usual values determination. However, urine collection during a day is difficult and numerous studies have been performed to replace the "gold standard" with measures on random samples and results given as protein/creatinine ratio or albumin/creatinine ratio, to decrease the variability. The paper presents the populations where ratios are well correlated with protein excretion, the cut-off values recommended in clinical settings and the limits of using ratio rather than 24 h excretion.