The bias between different albumin assays may affect clinical decision-making

Differences between laboratory assays can have important clinical implications. For creatinine assays this became apparent soon after the introduction of the Modification of Diet in Renal Disease formula and resulted in international efforts towards standardization. Albumin in blood is measured by different assays, either chromogenic using Bromocresol green (BCG) or Bromocresol purple (BCP), or by an immunoassay. Since differences between these assays have received limited attention we evaluated bias and imprecision of BCG and BCP assays in comparison to the immunoassay using blood samples from patients with membranous nephropathy and nephrotic syndrome. For the BCG assay, the mean bias was high (6.2 g/l, with a standard deviation of 2.4 g/l) compared to a bias of 0.3 g/l (standard deviation 1.5 g/l) for the BCP assay. Importantly, we questioned clinical relevance by evaluating the accuracy of the decision toward the use of prophylactic anticoagulant therapy. Notably, nephrologists may reach inappropriate treatment decisions using the BGC assay in up to 59% of patients. Thus, our study should stimulate efforts towards standardization of the albumin assays. Differences between laboratory assays can have important clinical implications. For creatinine assays this became apparent soon after the introduction of the Modification of Diet in Renal Disease formula and resulted in international efforts towards standardization. Albumin in blood is measured by different assays, either chromogenic using Bromocresol green (BCG) or Bromocresol purple (BCP), or by an immunoassay. Since differences between these assays have received limited attention we evaluated bias and imprecision of BCG and BCP assays in comparison to the immunoassay using blood samples from patients with membranous nephropathy and nephrotic syndrome. For the BCG assay, the mean bias was high (6.2 g/l, with a standard deviation of 2.4 g/l) compared to a bias of 0.3 g/l (standard deviation 1.5 g/l) for the BCP assay. Importantly, we questioned clinical relevance by evaluating the accuracy of the decision toward the use of prophylactic anticoagulant therapy. Notably, nephrologists may reach inappropriate treatment decisions using the BGC assay in up to 59% of patients. Thus, our study should stimulate efforts towards standardization of the albumin assays. The choice of the assay for measuring albumin has a major impact on routine laboratory valuesKidney InternationalVol. 96Issue 1PreviewIn their recent study comparing different assays to measure albumin level, van de Logt et al.1 show that the use of bromocresol green (BCG) (but not bromocresol purple [BCP]) leads to a substantial overestimation of plasma and serum albumin concentration (mean bias: 6.2 g/l), in comparison to the reference immunonephelometric assay in patients with hypoalbuminemia (including patients with membranous nephropathy, liver cirrhosis, or sepsis) and in chronic kidney disease patients with albumin concentrations within reference values. Full-Text PDF Albumin assays and clinical decision-making in nephrotic syndrome patientsKidney InternationalVol. 96Issue 1PreviewWith interest, we have read the article by van de Logt et al.,1 in which the importance of albumin assays in assessing hypoalbuminemia in nephrotic syndrome was highlighted. The investigators confirm the known bias for the various (dye binding) albumin assays and plead for improved standardization. Full-Text PDF