The relationship between urinary concentrations of protein and creatinine (PCR - protein / creatinine ratio) and of albumin and creatinine (ACR - albumin / creatinine ratio) is respectively used in the diagnosis of proteinuria and microalbuminuria.
This test partially replaces the traditional test based on the quantification of proteins in a urine sample collected over 24 hours, which sets the maximum normal limit at 150 mg of total protein in urine; higher protein concentrations are considered a sign of proteinuria.
As anticipated, in place of this test, one can resort to the study of the proteinuria / creatininuria or albuminuria / creatininuria ratio on a random urine sample, better in the morning. Based on the values of these indices, doctors speak of mciroalbuminuria and proteinuria, respectively.
When the albumin / creatinine ratio in urine (albuminuria / creatinuria) is between 3.5 mg / mmol and 35 mg / mmol in women and between 2.5 mg / mmol and 25 mg / mmol in males. The difference between male and female is linked to the fact that men - by virtue of the greater muscle mass - have higher urinary concentrations of creatinine. Other authors consider positive ratios between 30-300 μg / mg, which correspond to values of 3.5-35 mg / mmol for both sexes.
Above these values we speak of macroalbuminuria.
It is defined as such when the protein / creatinine ratio in urine (proteinuria / creatininuria) is equal to or greater than 45 mg / mmol (which is equivalent to an albuminuria / creatininuria ratio greater than 30 mg / mmol). Values below 2 mg / mmol are considered normal, while values above but below 45-50 mg / mmol are worthy of diagnostic investigations and adequate therapeutic interventions, especially in people with risk factors such as diabetes or hypertension (it is necessary better glycemic and blood pressure control and - given the increased cardiovascular risk - lipidemic).