Biological variation of ischaemia-modified albumin in healthy subjects.
OBJECTIVE
Ischaemia-modified albumin (IMA), as measured by the albumin-cobalt binding (ACB) test, 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 A CB test on a Roche modular analyser.


RESULTS
The analytical coefficient of variation (CV(A)) was 5%, and the within-subject (CV(I)) and between-subject (CV(G)) 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.


CONCLUSIONS
The ACB test 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.
Department of Chemical Pathology and School of Medicine, University of Pretoria, Pretoria, South Africa.
R
R
Govender
J
J
De Greef
R
R
Delport
P J
PJ
Becker
W J
WJ
Vermaak
D000328:Adult; D001741:Black or African American; D015415:Biomarkers / Q000097:blood; D003035:Cobalt; D015331:Cohort Studies; D003124:Colorimetry / Q000592:standards; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000097:blood / Q000175:diagnosis* / Q000208:ethnology; D011237:Predictive Value of Tests; D011485:Protein Binding; D011933:Reagent Kits, Diagnostic / Q000592:standards*; D012016:Reference Values; D015203:Reproducibility of Results; D012709:Serum Albumin / Q000378:metabolism*; D012737:Sex Factors; D044465:White People
D015415:Biomarkers; D011933:Reagent Kits, Diagnostic; D012709:Serum Albumin; D003035:Cobalt