Original article / research
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Evaluation of Ischaemia-modified Albumin by Cobalt Chloride Binding Assay in Coronary Artery Disease: A Cross-sectional Study |
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| Correspondence
Address : Dr. Soma Gupta, Professor and Head, Department of Biochemistry, NRS Medical College, 138 AJC Bose Rd, Kolkata-700014, West Bengal, India. E-mail: docsomagupta@gmail.com |
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Introduction: Ischaemia-modified Albumin (IMA) is an altered form of human serum albumin in which its N-terminal amino acids are modified due to ischaemia. IMA is produced when serum albumin is modified while circulating through ischaemic cardiac tissue, thereby reducing its binding capacity to heavy metal ions such as cobalt or nickel. This ability of albumin to bind to cobalt is diminished in patients with myocardial ischaemia, providing the basis for the albumin cobalt binding test for detecting IMA. Aim: To determine the level of IMA in Coronary Artery Disease (CAD) after standardising the parameter using the cobalt chloride binding method. Materials and Methods: This cross-sectional study was carried out from June 2018 to December 2019 at a tertiary care centre in the Department of Biochemistry and the Cardiology Department, NRS Medical College, Kolkata, West Bengal, India. A total of 100 CAD patients were included in the study, along with 100 age- and gender-matched healthy individuals (controls). IMA levels were measured in all study subjects by adding a known amount of cobalt (II) to serum samples and the unbound cobalt (II) was measured by the intensity of the coloured complex formed by adding mercaptoethanol, using a colorimeter at 470 nm. The difference in mean values between cases and controls was determined using the Student’s t-test. The precision of the assay was expressed as CV% {Standard Deviation (SD)/mean 100%}. To determine the cut-off value for serum IMA, an Receiver-operating Characteristic Curve (ROC) was plotted. Results: Among the 100 CAD patients, 49 were male and 51 were female. The mean age of the case group was 60.90±11.02 years, with a Body Mass Index (BMI) of 27.6±4.32 (kg/m2). The mean serum IMA level in cases was found to be significantly elevated in comparison to controls (89.77±10.73 and 49.35±10.68 u/mL, respectively). The standard curve was found to be linear up to 120 U/mL. The precision of the assay was expressed as Coefficient of Variation (CV %) (within run 4.23%, between runs 4.61%). The cut-off value for Serum IMA level was determined to be 74.23 u/mL. The diagnostic value of this cut-off level was calculated using standard formulas, which yielded diagnostic accuracy (87.00%), sensitivity (80.00%), specificity (94.00%), positive predictive value (93.02%) and negative predictive value (82.46%). Conclusion: The IMA can be used as an important biomarker to detect ischaemia in patients with CAD. |
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