engleski

Increased frequency of duplicate errors for LD IFCC method on Abbott Architect in Li-heparin plasma relative to serum samples

BACKGROUND-AIM The increased rate of discordant duplicate measurements was found in LD activity measurement in plasma on Roche platforms by some investigators. The aim of our study was to compare LD results on Abbott Architect c8000 analyzer in different processing settings: primary serum vs. primary plasma samples ; primary plasma samples centrifuged under different protocols and primary plasma vs. aliquoted plasma samples. METHODS All measurements were performed in duplicate on Architect c8000 (Abbott, Wiesbaden, Germany) emergency and routine analyzers on routine samples (N=1679) using Lactate dehydrogenase reagent (Abbott Laboratories, Illinois, USA) in undiluted protocol. Since predilution step consistently yielded inacceptable IQC results, we have done all testing in undiluted protocol. Following centrifugation protocols were used: 10 minutes at 1800g, 15 minutes at 1800g and 20 minutes at 1800g. Duplicate errors were considered if the difference between the two measurements exceeded the 95% confidence limits for the difference between the two results deviations. The 95% confidence limits were calculated using the formula: 95% confidence limit = [(R1 + R2)/2] * 0.028, where R1 and R2 represent the results for duplicate measurement of LD in each sample. RESULTS Duplicate errors were more frequent in primary plasma than in primary serum samples, on both analysers (P<0.001). Duplicate error rate did not differ respective to the centrifugation protocol (P = 0.962). There was a significant difference (P<0.001) between the error frequency in aliquoted plasma samples and primary plasma samples. CONCLUSION The sample of choice for LD measurement on the Abbot Architect c8000 is serum. Lithium heparin plasma samples produce unacceptably high frequency of duplicate errors and should not be used for LD measurements in undiluted protocol. Whether predilution step may reduce the error frequency, remains to be investigated.

preanalitical phase ; duplicate error ; lactate-dehydrogenase ; heparin plasma

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