Background The collection of blood samples in different vacutainers can affect the result of serum lithium estimation due to the presence of distinct additives in the blood collection vacutainer for enhancing the clot formation process. Due to the low therapeutic index and threat of toxicity of lithium, it is imperative to correctly report the test result. Thus, it has become a challenge for the laboratory physician to estimate lithium in any clinical laboratory setup. Materials and Methods Sample of 100 patients were collected and paired into clot activator vacutainers and plain glass vials. After centrifugation, samples from the paired collection tubes were processed immediately for serum lithium estimation by VITROS 4600 analyzer working on the principle of reflectance photometry. Both the paired tubes were stored at 2 to 8°C and were further analyzed, at 24 and 48 hours, respectively, from the time of their collection. The statistical analysis was done in IBM SPSS software version 23. Results There was a statistically significant differences between the mean of lithium values when processed within 1st hour of collection, obtained from clot activator vacutainers in comparison to glass vials. However, within tube comparison, there was no statistical difference in the lithium values estimated at 1st hour, 24 hours, and 48 hours of collection. Conclusion In this study, lithium values measured by clot-activated vacutainers are found to be lower as compared with values measured through glass vials.

Background: The collection of blood samples in different vacutainers can affect the result of serum lithium estimation due to the presence of distinct additives added in the blood collection vacutainer for enhancing the clot formation process. The presence of these additives has proven to interfere with laboratory results of biochemical analytes. In this case, both the pre-analytical and the analytical phases have a significant impact on the accuracy and precision of the test result. Thus, it has become a challenge for the lab physician to estimate lithium in any clinical laboratory setup. Materials and Methods: In total, 100 patient samples were collected and paired into clot activator vacutainers and plain glass vials. Both the paired collecting tubes after centrifugation were processed immediately via Vitros 4600 analyzer working on the principle of reflectance photometry. Both the paired tubes were stored at 2-8 degrees centigrade and were further analyzed, at 24 and 48 hours respectively, from the time of their collection. The statistical analysis was done in IBM SPSS software version 23. Results: There was a significant difference in the lithium values obtained from clot activator vacutainers in comparison to glass vial. The difference between the measurements of the lithium levels was statistically tested by t test where it was observed that the lithium measurements by the two different collecting tubes differed significantly with a Confidence Interval of 0.03 to 0.06 implying the level of agreement of both the methods are not similar. But there was no statistical difference in the lithium values estimated at 24 hours and 48 hours of collection. Conclusion: In this study, lithium levels measured by clot-activated vacutainers are found to be low as compared to lithium levels measured through glass vials. There is no apparent change in lithium values obtained at 1hr, 24hrs and 48hrs from their collection, when measured from the glass vials and the clot-activated vacutainers respectively, by the Vitros 4600 dry chemistry analyzer.