Lactate can also increase even when there is no evidence of oxygen deprivation. It can occur if patients have decreased activity of the enzyme pyruvate dehydrogenase or impaired lactate clearance due to hepatic dysfunction.
Pre-examination factors may also contribute. Plasma lactate concentration can be falsely increased if the plasma is not separated from the cells shortly after sample collection. Centrifugation and plasma separation from cells are 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. Ice should be used during transport, and a refrigerated centrifuge is recommended.
