engleski

Influence of hemolysis, icteria and glucose on activated aspartate and alanine aminotransferase (aAST and aALT) and non- activated aspartate and alanine aminotransferase (AST and ALT) activities

Background: The aim of this study was to evaluate interference of hemolysis, icteria and glucose on activated aspartate and alanine aminotransferase reagents (aAST and aALT) in comparison with non-activated enzyme forms (AST and ALT) in serum and plasma samples. Materials and methods: The study was carried out in University Department of Chemistry, Medical School University Hospital Sestre Milosrdnice, Zagreb, Croatia (July-October 2016). Hemolysis was achieved by mechanical trauma. Seven aliquotes of EDTA blood sample were drawn through the needle for increasing number of times ; hemolyzed plasma was separated after centrifugation (H index 0.4-14.9). For icteria and glucose interference testing, serum pool was spiked with exogenous bilirubin (Sigma-Aldrich, MO, USA) and 554 M glucose solution to achieve a final concentrations of 0-1000 µmol/L for bilirubin and 0-115 mmol/L for glucose. Enzyme activities and HIL indices were measured in duplicate on the Architect c8000 analyzer (Abbott, IL, USA) using original reagents. Bias calculated against the initial value was compared with external quality control criteria (ALT, aALT: 12%, AST, aAST: 15%). Results: For AST and aAST, hemolysis caused significant positive bias at the lowest level of hemolysis (bias: 29.6% and 32.4%, respectively). ALT and aALT activities were affected only in highly hemolyzed samples (H index: 8.9, bias: 17.2% for ALT and H index: 14.9, bias: 24.3% for aALT). Significant bias was observed in highly icteric samples for ALT (bilirubin: 745 µmol/L, bias: -38.9%), AST and aAST (bilirubin: 1017 µmol/L, bias: -70, 7% ; 22, 8%, respectivelly). Icteria didn´t cause significant changes in aALT activity. For glucose interference testing, all bias values were bellow acceptance criteria. Conclusion: Both forms of AST and ALT are affected in the same way by hemolysis (false increased) and glucose (no interference). High concentration of bilirubin interferes with AST and aAST, ALT but not with aALT.

preanalytical phase ; hemolysis ; icteria ; ALT ; AST

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