Lactate is a by-product of glucose metabolism. It is created when glucose is transformed into energy without oxygen present, in a process called anaerobic glycolysis. Lactate can also be produced in conditions with oxygen, but in smaller quantities.
Lactate levels are most often measured in hospitals to assess the patient's general condition and response to treatment, especially when there is a suspicion for a blood infection. However, a lactate test can also be ordered to assess an athlete's performance and exercise intensity of exercise.
Lactate is an important substance, as it is important to signal specific processes in the central nervous system. It is a biomarker for nerve abnormalities and tissue hypoperfusion, in which there is a small amount of oxygen reaching the tissues. It can also also help to assess the intensity of physical activity and muscle fatigue, as more lactate will be produced during periods of greater activity that require more oxygen and energy.
When it's tested
Lactate measurement is widely used in clinical practice to assess hospitalized patients, as well as to assess the intensity of physical activity and muscle fatigue in athletes.
In hospitals, lactate measurement is important to assess the patient's general condition and evaluate the response to treatment. The measurement is usually performed on hospitalized patients who are suspected of or have been diagnosed with sepsis or septic shock. These conditions are characterized by lactate levels above 2 mmol/L in addition to decreased blood pressure, rapid breathing, decreased urine production and mental confusion.
Lactate levels can indicate whether the patient is responding to treatment or can determine whether a change in treatment is needed.
In a sports setting, lactate levels can help to evaluate the athlete's level of performance and the intensity of the exercise. Very intense or prolonged physical activities, may require more oxygen, and lactate production is necessary to maintain cell activity. Therefore, measuring the amount of lactate after physical activity can help guide trainers to form appropriate training plans for athletes.
How the test is performed
A lactate test does not require fasting or any other type of preparation. Generally, People should avoid physical activity the day before the test, as exercise can alter test results
Normal lactate levels
The normal value for lactate in the blood can vary from lab to lab, but typically, normal lactate levels are between 5.7 and 22.0 mg/dL or 0.63 to 2.44 mmol/L, at rest. After exercise, it is common for the lactate levels to increase, however, no reference value has been established for this situation.
What does high lactate mean?
The main causes of high lactate are:
- Sepsis and septic shock, as the he production of toxins by microorganisms causes a decrease in oxygen levels, leading to an increase in lactate levels
- Intense physical activity, as cells need more energy than normal when exercising, and the oxygen available may not enough, leading to anaerobic glycolysis, and therefore more lactate
- Muscle fatigue: due to large amounts of lactate accumulated in the muscle
- Systemic inflammatory response syndrome (SIRS), as this condition is associated with a change in blood flow and immune system functioning. It stimulates an increase in lactate production in an attempt to maintain cellular activities and help resolve inflammation. With this conditions, lactate levels are monitored to evaluate the patient's response and the patient0s risk for organ failure
- Cardiogenic shock, in which there is an alteration in the blood and oxygen supply to the heart
- Hypovolemic shock, in which there is a large loss of fluids and blood, altering the distribution of blood to the tissues
Some studies have also shown that increased lactate can lead to cases of liver and kidney problems, diabetes mellitus, poisoning, and metabolic acidosis.