Blood test of lactic acid | what is lactic acid?

Lactic acid is produced in different tissues of the body when oxygen is lacking. This is particularly the case when practicing a physical activity. Its dosage is a blood test is prescribed to detect a possible lactic acidosis.
Lactic acid is produced in different tissues of the body when oxygen is lacking. This is particularly the case when practicing a physical activity. Its dosage is a blood test is prescribed to detect a possible lactic acidosis.

What is lactic acid?

Lactic acid is a substance produced by red blood cells, muscle cells, kidneys, skin cells, but also those of the heart, during the anaerobic degradation of glucose. It is a chemical process that occurs when oxygen is lacking and does not fully metabolize glucose. This is for example what happens during a myocardial infarction or muscle exercise too intense.
A blood test of lactic acid | what is lactic acid?

Note that under aerobic conditions, ie in the presence of oxygen, the end products of the use of glucose are not lactic acid but water and carbon dioxide.

Lactic acid and sport

When practicing a physical activity, the body needs more oxygen than it can produce by so-called aerobic processes. So he sets up anaerobic processes to produce energy. And lactic acid is the product of these chemical reactions.
Most of the lactic acid produced in the muscle cells pass into the blood and is removed from the muscle tissue within 30 minutes of stopping physical activity. Other tissues, such as the liver, kidneys or hearts, pick up lactic acid and use it as a source of energy.

What is the purpose of the analysis?

The doctor prescribes a lactic acid analysis to assess the state of oxidation of the tissues and to detect a possible lactic acidosis. It is a disorder of the acid-base balance of the body caused by an excess of lactic acid.
Some symptoms are characteristic of this attack. These include:
  • a decrease in blood volume (we speak of hypovolemia);
  • a state of shock;
  • a deep and rapid breathing (we speak of hyperventilation);
  • pains that are usually diffuse;
  • muscle cramps;
  • or nausea and vomiting.

How to interpret the results?

Normal lactic acid values in the venous blood range from 4.5 to 19.8 mg/dl.
Note that these reference values may change slightly depending on the laboratory medical analysis that performs the tests and the techniques they use.
When the values obtained are not included in this value range, it means that the tissues do not receive enough oxygen.
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lactic acid fermentation |  what is lactic acid | lactic acid definition

A higher lactic acid concentration may be a sign of:
  • liver disease
  • respiratory, renal or ventricular failure;
  • cardiac arrest ;
  • severe infection affecting the body as a whole (sepsis);
  • hypoxia, ie a low level of oxygen in the blood;
  • alcoholic intoxication;
  • Leukemia ;
  • or diabetes.

How is the analysis done? 

The examination consists of a venous blood sample, usually at the level of the bend of the elbow.
It is advisable not to exercise before doing the analysis, and to be fasting. The best option is even to take the sample after an extended rest of about 15 minutes.

What are the factors of variation?

In case of lactic acidosis, ie an excess of lactic acid in the body that accumulates faster than it can be metabolized, the treatment consists of an artificial ventilation and an infusion of bicarbonates.
In the particular case of the practice of a physical exercise, it is possible to slow down the accumulation of the lactic acid by being hydrated correctly (it is advisable to drink water before, during and after the training).
It should be noted that taking certain medications may cause the onset of metabolic acidosis. It is therefore essential to inform the doctor about your treatments, to show him your recent prescriptions.

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lactic acid fermentation |  what is lactic acid | lactic acid definition