Biological Variation of Ischaemia-Modified Albumin in Healthy Subjects : Cardiovascular Topic

ABSTRACT

Aim: Ischaemia-modified albumin (IMA); as measured by the albumin-cobalt binding (ACB) testr; has been cleared by the US Food and Drug administration as a biomarker to exclude the presence of myocardial ischaemia in patients. Although there are a number of published studies detailing the clinical utility of IMA; data on the biological variation of IMA are still lacking. In this study we determined the analytical and biological variance components of ischaemia-modified albumin; and compared the distribution of IMA values in our patient population to those provided by the kit manufacturer. Methods: IMA was determined once a week for five consecutive weeks on a cohort of healthy subjects using a colorimetric method; the ACB testr on a Roche modular analyser. Results: The analytical coefficient of variation (CVA) was 5; and the within-subject (CVI) and between-subject (CVG) biological variations were 3 and 7; respectively. Analysis of the repeated measures with gender and race (black and Caucasian) as between-subject factors; and weeks (1-5) as the within-subject factor showed that gender had no significant effect on circulating IMA concentrations (p = 0.3146); whereas race did have a significant effect (p = 0.0062). A significant (p = 0.0185) interaction was observed between gender and race. Conclusion: The ACB testr could bring a new dimension to the care and management of patients with acute coronary syndrome. Further studies for normal population distributions by gender and ethnicity; and an optimum cut-off value appear to be required