Berlin · New York A Diagnostic Programme for Quantitative Analysis of Proteinuria

Summary: A spectrum of quantitative methods was adapted to the Kone Specific Analyser for the purpose of recognizing, quantifying and differentiating various forms of proteinuria. Total protein, IgG, albumin and oci-microglobulin (measured by turbidimetry), N-acetyl-ß-.D-glucosaminidase activity and creatinine (measured photometrically), were measured in undiluted urine; in addition armicroglobulin was measured in serum. Within and between run predsion, accuracy and linearity of the turbidimetric methods were in good agreement with nephelometric procedures. All turbidimetric methods exhibited a correlation coefficient r> 0.98 when compared with the radial immunodiffusion procedure äs reference method. Total protein measured turbidi-metrically with the Kone Specific Analyser was in good agreement with the manual biuret procedure. The low detection limits and linearities allowed quantification of urine analytes from the lower ränge of normals up to ten times the upper limit of normals. The measured analytes exhibited stability in urine at pH 4—8 over at least seven days at 4 —6 °C and — 20 °C. Only IgG showed a significant loss (up to 30 percent), when measured after storage at —20 °C. Quantities per mol creatinine showed significantly lower intra-individual and inter-individual variability than quantities per liter. In 31 normal persons, the intraindividual Variation was lowest for N-acetyl-ß-Z>-glucosa-minidase activity (13%) and highest for total protein (33%), when measured in the second morning urine o