Evaluation of the effects of time, temperature, and specimen storage on in vitro lactate concentrations in healthy dogs.

BACKGROUND: Lactate concentrations increase significantly under certain storage conditions, except for when glycolysis-arresting agents are used. Evaluation of time and storage conditions on heparinized whole blood lactate concentrations without glycolysis-arresting agents have not been evaluated in dogs.

OBJECTIVES: The purpose of the study was to determine the effects of preanalytic storage conditions on the in vitro concentration of lactate in heparinized canine venous blood specimens.

METHODS: In this prospective study, blood collected from 30 healthy dogs was aliquoted and stored under different conditions: anaerobic refrigerated (3°C), aerobic refrigerated, anaerobic room temperature (RT), and aerobic RT. Whole blood lactate was analyzed at 15-25, 30-40, 60-70, and 120-130 minutes from time 0 (T0) under all storage conditions. Percent increases from the T0 specimen were calculated.

RESULTS: There were significantly increased lactate concentrations at all time points within the anaerobic refrigerated specimens compared to T0, and in the anaerobic RT specimens after 15-25 minutes. The aerobic refrigerated specimens did not have significant changes in lactate when compared to anaerobic refrigerated specimens, while the aerobic RT specimens had significant increases at all time points. Anaerobically refrigerated specimens stored < 40 minutes and aerobically refrigerated specimens stored < 25 minutes had in vitro lactate increases of < 20%.

CONCLUSIONS: Results support analyzing lactate specimens immediately. If lactate analysis is delayed, anaerobic refrigerated specimens should be analyzed within 40 minutes, and aerobic refrigerated specimens should be analyzed within 25 minutes. Room temperature specimens stored either aerobically or anaerobically should be avoided as lactate concentrations may be falsely increased.