Effect of albumin concentration and serum matrix on ischemia-modified albumin

Objectives:There is concern that ischemia-modified albumin (IMA) levels measured by albumin cobalt binding (ACB) assay reflect mainly albumin concentrations rather than myocardial ischemia.Design and methods:Serum matrix and proteins were separated from a serum pool by a membrane filter. Two series of pools with albumin concentrations of 10, 20, 30, 40, 50, and 60 g/L were prepared either with human albumin or serum protein fraction. IMA values of these pools were measured in quintiplicate.Results:There was a strong negative correlation between IMA and albumin levels in both pools. IMA change corresponding to each 10 g/L difference in albumin concentration was 37% and 48% in these pools.Conclusions:ACB assay reflects albumin concentrations rather than IMA. Primary predictor of IMA in serum matrix is albumin concentration.