An integrated microfluidic system for the determination of microalbuminuria by measuring the albumin-to-creatinine ratio

This study presents an integrated microfluidic system for the determination of microalbuminuria (MAU) through the measurements of the albumin-to-creatinine ratios in patients' urinary samples. Albumin concentrations are determined based on a non-immunological dye binding assay in which the dyes react specifically with albumin to undergo a strong fluorescence enhancement. Creatinine concentrations are determined based on the Jaffé reaction in which the reagents react specifically with creatinine to form orange-red colored complexes. Two calibration curves for determining the concentrations of urinary albumin and creatinine are constructed with assay ranges of 5-220 and 1-100 mg/l, respectively. Using this system to determine the ACRs of collected clinical urine samples, statistical tools including Bland-Altman bias plot and Passing-Bablok regression analysis show that the results obtained by the proposed microfluidic system are in good agreement with those obtained by conventional methods. This simple, automatic, inexpensive, and microchip-based platform demonstrates a promising alternative to the conventional assays for determining MAU and may be suited for clinical applications. © 2010 Springer-Verlag.