QUANTITATIVE-DETERMINATION OF TOTAL URINARY PROTEIN UTILIZING THE PRINCIPLE OF COOMASSIE BRILLIANT BLUE G250 BINDING TO PROTEIN

  • 1 January 1981
    • journal article
    • research article
    • Vol. 19  (4) , 203-208
Abstract
Coomassie Brilliant Blue G250 (CBB) was used for the determination of total urinary protein and compared with the biuret-procedure. In the CBB assay 0.10 ml urine are added to 50 ml CBB reagent and the sample is read against the reagent blank. This method seems to be superior to the biuret-procedure because of better reproducibility,higher sensitivity and simpler handling. The upper limit of urinary protein excretion in 49 healthy subjects was 120 mg/24 h. To evaluate the clinical significance of the method the urinary protein concentration of 134 patients with metabolic, systemic and organ diseases was compared with the biuret-procedure. The regression line was y = 0.827 x + 8.713 mg/l with a correlation coefficient of r = 0.966. The type of proteinuria (mixed, glomerular, tubular) had no influence on the protein value measured with the CBB method. In selective proteinuria, like Bence-Jones protein excretion, there is no correlation between the 2 methods, because the concentration of Bence-Jones protein is underestimated. Lower protein values were also frequently obtained for patients with diabetes mellitus. Some specimens from patients with chronic renal failure treated by hemodialysis showed elevated values. In spite of these limitations the CBB method may be the method of choice for the determination of total urinary protein.

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