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Background Myeloperoxidase has shown potential as a marker for prognosis of coronary artery disease, but presently little is known about preanalytical handling of samples for quantifying myeloperoxidase. The present study was conducted to evaluate the effect of collection tube and freeze-thaw cycles on myeloperoxidase concentrations. Methods Acute coronary syndrome patients ( n = 88) were enrolled after obtaining written informed consent from coronary care unit of a tertiary care hospital (January 2012-June 2014). About 5 mL venous blood was collected from patients and divided into serum, lithium heparin, ethylenediaminetetraacetic acid and sodium citrate tubes. Except serum, all tubes were kept on ice immediately after collection. Samples were centrifuged at -4℃, separated immediately after centrifugation and stored at -40℃ until analysis. Myeloperoxidase was quantified by in-house and commercial assays and re-quantified after five freeze-thaw cycles. Results Myeloperoxidase concentrations, (serum samples) determined by commercial and in-house assays correlated well (r = 0.946) ( P < 0.001) and were higher in serum samples. Within plasma, myeloperoxidase concentrations were slightly higher in ethylenediaminetetraacetic acid (307.7 ± 52.1) and lower in lithium heparin (290.3 ± 49.2) and sodium citrate (221.4 ± 40.3) but not statistically significant. Correlation between myeloperoxidase concentrations (in-house enzyme-linked immunosorbent assay) after first cycle and fifth freeze-thaw cycle dropped to r = 0.448 ( P < 0.001). Conclusion Myeloperoxidase concentrations are comparable in three types of plasma tubes when samples are placed on ice immediately, centrifuged at low temperatures and separated immediately after centrifugation. Multiple freeze-thaw cycles have an effect on myeloperoxidase and should be avoided for quantifying myeloperoxidase.

C-reactive protein (CRP) is intricately sensitive marker of inflammation, infection, and tissue damage. Role in the prognosis of heart diseases has been recently discovered. This study aimed to develop a cost-effective and high-sensitivity CRP immunoassay for use in cardiac risk assessment. Assay was optimized for coating, blocking of capturing antibody, dilution, and reaction time of the conjugate and sample volume. For normal reference range, CRP was determined in serum samples from apparently healthy volunteers. For clinical validation, CRP was determined in samples of acute coronary syndrome patients by in-house and commercial assays. The lower detection limit of in-house assay was 0.16 µg/L. Intra and inter assay imprecision was 4.39%, 4.6% and 8.6%, 9.3%, respectively. The correlation between the CRP levels by the two assays was r = 0.861. Sensitivity, specificity, predictive value for a positive test, and a negative test of in-house assay was 95.3%, 92.8%, 95.3%, and 92.8%, respectively. At lower-end CRP levels of both kits correlated very well but showed variation at upper end. In-house assay showed high sensitivity and reliability at lower end and it is hoped that will help to evaluate cardiac risk assessment (after improvement at upper end) in clinically poor settings. [ABSTRACT FROM PUBLISHER]

Objective: The aim of the present study was to evaluate the role of C-reactive protein (CRP), leukocyte count and myeloperoxidase (MPO) in predicting adverse outcomes in acute coronary syndrome patients. Methodology: Ninety consecutive patients with acute coronary syndrome (ACS) were enrolled from Coronary Care Unit of Shaikh Zayed Hospital, Lahore from January 2012 to April 2013. Baseline leukocyte count was determined by Abacus cell counter while CRP and MPO levels were determined by using commercially available enzyme immunoassays. Mortality and adverse cardiac events were recorded for a follow up period of 6 months. Results: Out of ninety patients 65 (72.2%) were males. Mean age of patients was 56.25±13.01 years (male patients 55.43±14.02 while female patients 58.4±9.88). Number of adverse events was highest (18.6%) in CRP > median category, followed by leukocyte count > median (17.9%) and MPO > median category (17.1%), respectively. Adverse event rate was found to be significantly higher (p = 0.043) in CRP > median category as compared to CRP < median category. Adverse event rate was also higher (p = 0.08) (clinically significant) in > median category of leukocyte count but in case of MPO level it did not reach level of statistical or clinical significance (p = 0.12). Conclusion: CRP is a predictor of adverse outcome in acute coronary syndrome patients and may serve as a marker in prognosis of ACS. Further studies with large sample size are required for confirmation of predictive role of leukocyte count. [ABSTRACT FROM AUTHOR]