Lactate can also be increased even when there is no evidence of oxygen deprivation. Increased lactate can occur if patients have decreased activity of the enzyme pyruvate dehydrogenase or impaired clearance of lactate as a result of hepatic dysfunction.
Preanalytic factors may contribute, as well. Plasma lactate concentration can be falsely increased if the plasma is not separated from the cells shortly after sample collection (Centrifugation and separation of plasma from cells is recommended within 15 minutes of collection). Blood cells continue to metabolize glucose following collection, resulting in the production of lactic acid. For this reason, a gray-top tube containing sodium fluoride, which inhibits glycolysis, is usually recommended for plasma lactate sample collection. The use of ice during transport and the use of a refrigerated centrifuge are also recommended.
