Ischemia – modified albumin by albumin cobalt binding test: a false myth or reality

Abstract

Abstract Scientific knowledge should be based on evidence. However, some scientific studies can be carried out without sufficient evidence. And these studies may mislead subsequent studies. Ischemia-modified albumin (IMA) is a relatively newly proposed biomarker. It is used not only for myocardial ischemia but also used for other pathological conditions in the body. IMA is commonly measured by albumin cobalt binding (ACB) assay. ACB is a simple colorimetric assay performed in patients’ sera. It is claimed that because of the ischemia or ischemia-reperfusion, the molecular structure of the N-terminus of human serum albumin is changed and therefore it cannot bind metal ions and cobalt ions added into the reaction mixture react with dithiothreitol to give a brown color. The clinical performance of the ACB assay is poor and it has not a strong correlation with other ischemia biomarkers. There are many analytical uncertainties in ACB assay and IMA as well. Despite the uncertainties, the ACB assay is still commonly used for many research studies. Therefore the theory of the ACB assay should be questioned. In this opinion paper, we discussed these uncertainties. In conclusion, there is insufficient evidence for the existence of IMA as a biomarker. The ACB assay essentially measures serum albumin concentration. There are many other interfering factors with the ACB assay. Therefore, the measurement of IMA in any pathological condition is a useless effort.