Background: Approximately 2/3 of all pre-analytical errors occur in the pre-analytical phase, where mixing of sample tubes directly after sampling is one of the factors. The purpose of the study was to compare the analytical results for the glucose, lactate dehydrogenase and potassium in serum from mixed tubes with unmixed tubes. The study's aim was also to investigate the durability of these three analytes at room temperature (25 °C) for seven days.
Method: 100 mixed and 100 unmixed serum tubes with gel, from 100 patients, were analyzed on Architect ci2800. Assay results were statistically compared with the paired t-test. All the serum tubes were stored at room temperature for seven days and the three analytes were analyzed daily. The results of the analysis were compared statistically by ANOVA.
Results: No statistical significant difference (p > 0,05) was found for glucose and potassium between the unmixed and mixed tubes. Lactate dehydrogenase showed a small but statistical significant difference (p < 0,05) between the unmixed and mixed tubes. The differences in durability between day 1, day 2 and day 7 of the glucose, lactate dehydrogenase and potassium was found to be statistic significant (p < 0,05).
Conclusion: This study indicates that it is not necessary to mix the serum tubes immediately after the blood sampling, however it is important to mix other types of tubes, such as citrate tube. Therefore it is good to create a routine while you are mixing all the tubes. Glucose is the most stable analyte in room temperature for seven days while the potassium is the least stable.