An improved microalbumin method (µALB_2) with extended analytical measurement range evaluated on the ADVIA ® chemistry systems

Quantitative determination of albumin (ALB) in human urine is important to assess kidney functions in a variety of diseases. Recently, Siemens released an improved Microalbumin assay (µALB_2) to measure urinary ALB on the automated, random access ADVIA 1650/1800, ADVIA 2400, and ADVIA 1200 Chemistry Systems. We evaluated analytical performances of this new method. All ADVIA Chemistry Systems use the same microalbumin reagent packs, µALB_2 calibrators, and commercial controls. The within‐run and total CVs of the improved method with two‐level BioRad Liquichek Urine Chemistry controls (∼2 and 9 mg/dl ALB) and a urine pool (∼29 mg/dl ALB) on all ADVIA Chemistry systems were <4.1 and <6.1%, respectively (40 replicates per sample). The analytical range/linearity of the method (all ADVIA systems) was from 0.3 mg/dl to theALB concentration in the highest level of calibrator (∼38–42 mg/dl). The improved method (µALB_2) on the ADVIA 1650/1800 ( y ) correlated well with both the Beckman DXC 800 Microalbumin and the old microalbumin method on the ADVIA 1650/1800 analyzers. The improved method showed <10% interference with 16 chemicals from acetaminophen to uric acid that may be present in urine. The improved method has a minimum of 60 days' on‐system stability on all systems with the calibration frequencies of (with/without a Reagent Container insert) 20/30 days (ADVIA1200), 50/60 days (ADVIA1650/1800), and 20/60 days (ADVIA2400). No prozone was observed with the method on any platform up to the highest ALB concentration tested in a sample (4,000 mg/dl). J. Clin. Lab. Anal. 23:314–318, 2009. © 2009 Wiley‐Liss, Inc.