Effect of Time and Temperature on Anticoagulant‐dependent Pseudothrombocytopenia in Göttingen Minipigs

BackgroundA marked decrease in thrombocyte count was observed between subsequent measurements of the same EDTA blood sample in several minipigs, but little information was available explaining this finding. ObjectivesThe objective was to evaluate the impact of several preanalytic variables on thrombocyte counts in minipigs, in order to improve understanding of the invitro thrombocyte decrease observed. Materials and MethodsHematology blood samples from male and female Gottingen minipigs were collected using EDTA or citrate as an anticoagulant. Samples were stored under different conditions (room temperature, 4 degrees C, or 37-38 degrees C) and were analyzed approximately 0.5 to oneh, 3.5-4h, 7-7.5h, and 28-29h after collection. ResultsIn EDTA blood samples from male minipigs stored at room temperature, there was a progressive thrombocyte decrease over time up to -71% after 29h, caused by invitro aggregation. In females, no consistent change was seen up to 7.5h, but there was a decrease up to -47% after 29h. Thrombocyte count was most stable during storage at 4 degrees C. No consistent marked decrease in thrombocyte counts was seen for citrated blood at room temperature, although such a decrease was present in a few individual animals. ConclusionsStudy results provide evidence for an anticoagulant-dependent pseudothrombocytopenia in minipigs progressing over time and depending on the storage temperature of the blood sample. It is therefore recommended to perform thrombocyte counts as soon as possible after blood collection, and in case of low counts, investigate for the presence of artifactual platelet clumping.