Performance characteristics of an HPLC method for Urinary Albumin

Microalbuminuria is a marker of early diabetic nephropathy and cardiovascular risk. Immunoassays for urinary albumin can underestimate the amount of intact albumin present in urine. The purpose of this study was to evaluate a new urinary albumin assay that employs size exclusion HPLC with UV detection to quantify urinary albumin. We determined the limit of detection (LOD), linearity, imprecision, comparison to an immunoturbidimetric assay (ITA), and pediatric and adult reference intervals on random urine collections. The HPLC assay for total urinary albumin shows acceptable performance and quantifies albumin species not detected by immunoassay. Our studies of apparently healthy children and adults suggest the need for separate male and female and pediatric and adult reference intervals. Further outcome studies are necessary to determine how to best interpret urinary albumin measurements made by HPLC.