Blood lactate, also known as 2-hydroxypropanoic acid, lactic acid, or l-lactate, is an end product of anaerobic glycolysis as an alternative to pyruvate entering the Krebs cycle, enabling metabolism of glucose. Major sites of production are skeletal muscle, brain, and erythrocytes. Lactate is metabolized by the liver.
Normal range: 0.3 " “2.4 mmol/L.
Critical value: >5 mmol/L.
Use
Monitoring of metabolic acidosis, lactic acidosis
Interpretation
Increased In
Hypoperfusion: CHF, shock
Decrease oxygen content: hypoxemia, severe anemia, carbon monoxide poisoning
Sepsis
DKA
Drugs and toxins (e.g., Ringer lactate solution, biguanides, retroviral therapy, isoniazid, acetaminophen, ethanol, ethylene glycol, and others)
Strenuous exercise
Seizures
Liver failure
Kidney failure
d-Lactate acidosis (due to short bowel syndrome or other forms of malabsorption)
Proper specimen collection and processing techniques are critical for reliable results. Use of tourniquet or clenching hands increases lactate.
This test does not measure d-lactate, an uncommon, often undiagnosed cause of lactic acidosis.
A lactate/pyruvate ratio may be used to differentiate between causes of lactic acidosis. Certain congenital disorders in which pyruvate is not converted to lactate, for example, pyruvate dehydrogenase deficiency. In this case, pyruvate will accumulate, blood levels will be high, and the lactate/pyruvate ratio will be low.