Performance characteristics of an HPLC assay for urinary albumin.
Microalbuminuria is a marker of diabetic nephropathy and cardiovascular risk. Immunoassays underestimate the amount of intact albumin present in urine. The purpose of this study was to evaluate a new urinary albumin assay that uses size exclusion high-performance liquid chromatography (HPLC). We determined the limit of detection, linearity, imprecision, a comparison with an immunoturbidimetric assay, and pediatric and adult reference intervals. The limit of detection was 3.4 mg/L. The assay was linear from 4 to 240 mg/L. Total imprecision was less than 10% from 16 to 206 mg/L. Comparison of the albumin/creatinine ratio by HPLC with an immunoturbidimetric method showed positive proportional bias, which decreased with increasing concentrations of albumin. Nonparametric reference intervals were 22 to 250 mg/g for girls, 20 to 130 mg/g for boys, 14 to 62 mg/g for women, and 10 to 37 mg/g for men. This HPLC assay for urinary albumin shows acceptable performance and quantifies albumin species that are not detected by immunoassay. Separate reference intervals for children and adults seem necessary.
Owen
William E
WE
ARUP Institute for Clinical and Experimental Pathology, University of Utah, Health Sciences Center, Salt Lake City, USA.
Roberts
William L
WL
D000328:Adult; D000367:Age Factors; D000419:Albuminuria / Q000175:diagnosis* / Q000209:etiology; D002648:Child; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003920:Diabetes Mellitus / Q000175:diagnosis; D003928:Diabetic Nephropathies / Q000150:complications / Q000175:diagnosis; D005260:Female; D006801:Humans; D007118:Immunoassay; D008297:Male; D009391:Nephelometry and Turbidimetry; D012680:Sensitivity and Specificity; D012737:Sex Factors