The pre-analytical phase is known for being the most important step in the laboratory process to reach reliable test results. If handling, transport or preparation of the sample is performed incorrectly the results can deviate from the true value. Today, sampling tubes contains various additives to stabilize concentration levels. The aim of this study was to test a new sampling tube containing fluoride/citrate for glucose, lactate and homocysteine. It was also of interest to evaluate the stability of those three analytes in lithium-heparin, sodium-fluoride/potassium oxalate and fluoride/citrate tubes. To perform the sustainability study, a method verification was done for homocysteine in plasma. The study was performed in a hospital laboratory on the routine instrument Roche Cobas 6000 analyzer. Blood was drawn from 20 patients and was analyzed at the hospital laboratory in Gävle. The blood samples were transported frozen to the laboratory in Hudiksvall and were used in the method verification. For the sustainability study, blood was drawn from 10 healthy volunteers in lithium-heparin, sodium-fluoride/potassium oxalate and fluoride/citrate tubes. The method verification was approved. The results showed that glucose was stable for up to 72 hours in Vacuette Glycaemia tube with fluoride/citrate and this tube also gave more accurate results. Lactate and homocysteine were also stable in fluoride/citrate, but needs further studies. All three analytes were more stable if the sample tubes were centrifuged as soon as possible after blood collection. Fluoride/citrate tubes were stable without centrifugation directly.

In order to keep the turnaround time it is desirable to have few centrifugal programs and be able to centrifuge microtainer tubes together with vacutainer tubes. BD has launched a new type of microtainer tube that got a lower g-force than the older one on the same centrifugation program. The aims was to compare this program and three other, more powerful, programs and compare the impact on some common analytes and serum indices, especially on hemolysis. Three test parts was performed using venous samples taken from healthy individuals, 1) transfer of whole blood from serum tube to microtainer tubes, a clinical chemistry analysis; 2) whole blood from plasma tube to microtainer tubes, a clinical chemistry analysis and 3) whole blood from plasma tube to microtainer tubes for platelet count analysis. All tubes were examined for gel formation. The result showed a significant variance between some settings for some analytes but foremost at 899g and at 2000g, both in 10 min. The platelet count was below the threshold limit at 2000g. No tube had insufficient formation of the gel. The setting of 2000g was found suitable for microtainer tubes. These results correspond with the recommended settings from BD. Further studies are needed with more analytes and test subjects and a simulated transport time for plasma, because of the increased risk for hemolysis, to confirm if the same setting can be used for microtainer tubes (899g) as for the older microtainer tube and vacutainer tube (1300g).