engleski

Data analysis of surrogate markers for detection of K-EDTA contamination

Introduction: There is ongoing debate among laboratory professionals on one of the recommended steps in phlebotomy procedure – order of draw. Many contradictory data on K- ethylenediaminetetra acetic acid (K-EDTA) contamination of samples as consequence of non- compliance to order of draw are published. Analytes commonly used as surrogate markers of K-EDTA contamination are potassium (K), calcium (Ca) and magnesium (Mg). Aim of our study was to assess frequency of K-EDTA contamination on samples analyzed in our laboratory during one- year period by data analysis of surrogate markers. Materials and Methods: We extracted data from our Laboratory Information System (LIS) for one–year period (from April of 2014 to April of 2015). Creatinine, potassium, calcium and magnesium results were analyzed for patient samples collected at hospital wards and outpatient samples. Greiner Bio One collection devices were used for collection of samples. Samples were analyzed on Abbott Architect c8000 biochemistry analyzer. Creatinine concentration >150 μmol/L was defined as cut-off for kidney function disorder, while concentration of K ≥5.5 mmol/L was considered as hyperkalemia. Cut-off for hypocalcaemia was Ca <2.14 mmol/L and for hypomagnesaemia it was Mg <0.65 mmol/L. Data were analyzed using Microsoft office excel 2003 program. Results: Data from 50435 samples were analyzed. Out of total number (N=50435), there were found 812 (1.6%) samples with hyperkalemia. For those samples (N=391, 0.8%) having creatinine concentration <150 μmol/L, pseudohyperkalemia was suspected. In that sample group, we found N=31 (0.06%) samples having hypocalcaemia, while hypomagnesaemia was not found. Conclusion: Based on this retrospective data analysis on surrogate markers we conclude that K-EDTA contamination of samples is not preanalytical error in our laboratory.

preanalytical phase ; laboratory error ; EDTA contamination

nije evidentirano