Analytical validation of an HPLC assay for urinary albumin

Abstract

Results The HPLC assay was linear to 963 mg/l with a limit of detection of 6.1 mg/l. Within-run and between-run precision was < 2% and 7–10%, respectively. Unpreserved urine was stable for at least 3 days at room temperature and 10 days at 4 °C. In both diabetic and nondiabetic subjects urinary albumin concentrations were higher by HPLC than by ITA, and many more diabetic and nondiabetic individuals were classified as microalbuminuric by HPLC than by ITA. The HPLC assay showed acceptable performance; however, because urinary albumin concentrations are higher in apparently healthy nondiabetic as well as diabetic subjects, different cutpoints will be necessary to accurately differentiate microalbuminuria. Conclusions Prospective studies are necessary to determine whether the HPLC assay can effectively detect microalbuminuria earlier than current assays without a concomitant increase in the false positive rate.