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

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. This is a chemical process that occurs when oxygen is lacking and it does not allow glucose to be metabolized completely. This is for example what happens during a myocardial infarction or too intense muscular exercise.

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

When participating in 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 muscle cells passes into the blood and is eliminated from muscle tissue within 30 minutes of stopping physical activity. Other tissues, such as the liver, kidneys or even the heart, capture lactic acid and use it as a source of energy.

The doctor prescribes a lactic acid analysis to assess the oxidation state of the tissues and detect any lactic acidosis. It is a disorder of the acid-base balance of the body caused by an excess of lactic acid.

Certain symptoms are characteristic of this attack. These include:

• a decrease in blood volume (this is called hypovolaemia);
• a state of shock;
• deep and rapid breathing (this is called hyperventilation);
• pain that is usually diffuse;
• muscle cramps;
• or even nausea and vomiting.

Normal values ​​of lactic acid in venous blood are between 4,5 and 19,8 mg / dl.

Note that these reference values ​​may change slightly depending on the medical analysis laboratory that performs the tests and the techniques they use.

When the values ​​obtained are not within this range of values, it means that the tissues are not receiving enough oxygen.

A higher concentration of lactic acid can be a sign of:

• liver disease;
• respiratory, renal or ventricular failure;
• cardiac arrest ;
• a severe infection affecting the body as a whole (sepsis);
• hypoxia, ie a low level of oxygen in the blood;
• alcohol poisoning;
• a leukemia ;
• or a diabetes.

The examination consists of a sample of venous blood, generally at the level of the elbow crease.

It is advisable not to do any physical exercise before doing the analysis, and to be on an empty stomach. The best option is even to take the sample after lying down for about 15 minutes.

In case of lactic acidosis, i.e. an excess of lactic acid in the body which accumulates faster than it can be metabolized, the treatment consists of 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 lactic acid by hydrating properly (it is advisable to drink water before, during and after training) .

Note that taking certain drugs can be the cause of the occurrence of metabolic acidosis. It is therefore essential to inform the doctor about your treatments, to show him your recent prescriptions.