Lactate (plasma)

Plasma

1 mL

0.5 mL

Sterile screw capped vial

Collect 2-4 milliliters of blood in sodium fluoride (gray top) tube. Immediately immerse tube in ice at time of collection; spin specimen ASAP. Freeze plasma@-20°Celsius or below. Preferred volume: 1.0 milliliter, minimum volume: 0.5 milliliter

Freeze as soon as possible after collection; Ship within 24 hours. Ship samples priority overnight on 3-4 lbs of dry ice. Sample must arrive in our lab Monday - Saturday. We do NOT accept Sunday or holiday deliveries.

Room Temperature: Not stable; Refrigerated: 24 hours; Frozen: 72 hours @ -20C, Indefinitely @ -80C; Freeze/Thaw: None

Incorrect specimen type received; Sample received thawed; Sample received hemolyzed or contaminated with blood

Plasma lactate (MET08) is used for diagnosing and monitoring patients with lactic acidosis.

Lactate is the end product of anaerobic carbohydrate metabolism. Major sites of production are skeletal muscle, brain, and erythrocytes. Lactate is metabolized by the liver. The concentration of lactate depends on the rate of production and the rate of liver clearance. The liver can adequately clear lactate until the concentration reaches approximately 2 mmol/L. When this level is exceeded, lactate begins to accumulate rapidly. For example, while resting lactate levels are usually <1 mmol/L, during strenuous exercise levels can rise >20 mmol/L within a few seconds. Lactic acidosis signals the deterioration of the cellular oxidative process and is associated with hyperpnea, weakness, fatigue, stupor, and finally coma. These conditions may be irreversible, even after treatment is administered. Lactate acidosis may be associated with hypoxic conditions (eg, shock, hypovolemia, heart failure, pulmonary insufficiency), metabolic disorders (eg, diabetic ketoacidosis, malignancies), and toxin exposures (eg, ethanol, methanol, salicylates). Lactate elevations can be observed in hereditary metabolic diseases such as mitochondrial diseases. Lactate may suggest an inborn error of metabolism as some present with lactic acidosis and/or a high Lactate:Pyruvate ratio. The Lactate:Pyruvate ratio is elevated in several, but not all, mitochondrial respiratory chain disorders. Mitochondrial disorders vary widely in presentation and age of onset. Many mitochondrial disorders have neurologic and myopathic features and may involve multiple organ systems. Determination of lactate, pyruvate, and Lactate:Pyruvate ratio in cerebrospinal fluid is helpful in directing attention toward a possible mitochondrial disorder in cases with predominantly neurologic dysfunction and normal blood lactate levels, though further confirmatory testing will be required to establish a diagnosis. A low Lactate:Pyruvate ratio is observed in inherited disorders of pyruvate metabolism including pyruvate dehydrogenase complex (PDHC) deficiency. Clinical presentation of PDHC deficiency can range from fatal congenital lactic acidosis to relatively mild ataxia or neuropathy. The most common features in infants and children with PDHC deficiency are delayed development and hypotonia, and seizures and ataxia are also frequent features. Other manifestations can include congenital brain malformations, degenerative changes including Leigh disease, and facial dysmorphism. An elevated Lactate:Pyruvate ratio may indicate inherited disorders of the respiratory chain complex, tricarboxylic acid cycle disorders and pyruvate carboxylase deficiency. Respiratory chain defects usually result in Lactate:Pyruvate ratios >20. A low Lactate:Pyruvate ratio (disproportionately elevated pyruvic acid) may indicate an inherited disorder of pyruvate metabolism. Defects of the pyruvate dehydrogenase complex result in Lactate:Pyruvate ratios <10. The Lactate:Pyruvate ratio is characteristically normal in other patients. An artificially high ratio can be found if the patient is acutely ill. Cerebrospinal fluid (CSF) Lactate:Pyruvate ratio may assist in evaluation of patients with neurologic dysfunction and normal blood Lactate:Pyruvate ratios. Blood and CSF specimens should be collected at the same time. While no definitive concentration of lactate has been established for the diagnosis of lactic acidosis, lactate concentrations exceeding 5 mmol/L and pH <7.25 are generally considered indicative of significant lactic acidosis.

Enzyme/UV