[New trends in the laboratory diagnostics of proteinuria and albuminuria]

According to current clinical trials, albumin excretion is an early indicator of cardiovascular damage. While proteinuria is considered as a marker of kidney function, albuminuria indicates cardiovascular risk first of all. Sensitivity of the previous laboratory tests does not meet the clinical requirements, and the error of urine collection makes the results misleading. For that reason recent guidelines suggest to calculate albumin/creatinine (ACR) and protein/creatinine (PCR) measured from the first morning urine. For the clinical diagnosis of albuminuria the sensitive immunoturbidimetric assays are suggested. Albumin dipsticks are not recommended for the measurement of albuminuria. Wide-range urinary protein reagents are also available with high sensitivity, while serum reagents are not applicable (Biuret). The traceability of calibrator to a reference material is a critical requirement. Proteinuria and albuminuria of a patient should be monitored in the same laboratory, using a fixed method and cut-off value. Albumin/creatinine value should be reported together with gender-dependent reference range.