Lactic Acid is a by-product of carbohydrate metabolism. Blood lactate arises primarily from muscle cells and erthrocytes and is metabolised by the liver. Therefore, blood lactate levels reflect both production and metabolism.
METHOD Enzymatic, Colourimetric
PRINCIPLE Lactic acid is converted to pyruvate and the H2O2 (Hydrogen Peroxide) by lactate oxidase. In the presence of the H2O2 formed, peroxidase catalyzes the oxidative condensation of chromogen precursors to produce a coloured dye with an absorption maximum at 540 nm. The increase in absorbance at 540 nm is directly proportional to lactate concentration in the sample.
DIAGNOSTIC IMPLICATIONS Normal lactate acid levels are 4.5-19.8 mg/dL. Elevate lactate acid levels can result from severe tissue oxygen deprivation leading to ‘lactic acidosis’ characterised by weakness, stupor, fatigue and coma. Lactate measurement can also be useful clinically in the diagnosis of angina pectoris or in liver function testing where reduced liver function is suspected.