MCV (blood test): decoding. MCV: norm

Counting the number of erythrocyte cells, determining their average volume or in analyzing blood in combination with other studies are used to conduct differential diagnosis of various forms of anemia and other pathological conditions.

What is red blood cells

According to the characteristics of red blood cells (red blood cells), which belong to highly specialized nuclear-free blood cells of biconcave form, one can judge the state of human health. In erythrocyte cells, there is a respiratory pigment - an iron-containing protein called hemoglobin. The main function of erythrocytes is the transfer of oxygen, which is very important for the functioning of all organs in the body. The formation of these cells is responsible for the red bone marrow. This process is stimulated by erythropoietin, which is produced in large volume by kidney cells under conditions of hypoxia.

Normal hemoglobin synthesis and the formation of red blood cells are possible only in the presence of cyanocobalamin and folic acid, as well as a sufficient intake of iron ions. In the systemic circulation, erythrocytes exist about 4 months. Then the destruction of blood cells takes place, the place for their disintegration is the spleen and reticulo-endothelial system.

What does MCV mean?

The MCV index is an erythrocyte index that characterizes the mean red blood cell volume. To establish an accurate diagnosis of the disease, doctors always prescribe a clinical blood test. Decoding MCV speaks about the state of blood cells in the human body. In healthy people, the ratio of erythrocytes to the total volume of blood is constant, which means that their size and quantity should not change.

On the development of allergies, inflammatory processes, the lack of vitamins and minerals can be found by submitting MCV-analysis of blood. The interpretation of its results, showing deviations from the norm, indicates possible pathological conditions.

This indicator is determined both in the course of the general clinical analysis of blood, and in the form of a separate study.

How to calculate MCV

To calculate the average volume of erythrocyte, it is necessary to divide the sum of the cell volumes into the total number of erythrocyte blood cells. Another way of calculating is based on dividing the hematocrit index or the number for 1 mm ^{3 of} blood by the number of all red blood cells. A hematocrit means a percentage ratio between the volume of blood cells and the total volume of blood.

On MCV, a blood test, the decoding of which is related to the evaluation of the size of red blood cells, is considered less accurate than two other methods of calculation. This is due to the fact that when the diameter of the erythrocyte cell changes by 5%, its volume changes by 15%. The reliability of this indicator can be distorted when there is a large number of erythrocytes in which the shape is changed. For example, if you perform a general blood test, the MCV value will be normal if the patient has both macro- and microcytosis.

It should be borne in mind that in microspherocites the diameter is usually underestimated, but the average volume is within the normal range, which is why the microscopy of the blood smear is always recommended.

unit of measurement

For the unit of measurement of the mean erythrocyte volume (MCV), femtoliters (fl) or cubic micrometers (μm ³ ) are adopted.

What does the analysis show?

With the help of this blood indicator, various types of anemia that require specific treatment are diagnosed.

Results MCV in the analysis of blood can distinguish:

• Microcytic anemia with deficiency of iron ions and thalassemia, when the synthesis of the polypeptide chain, which is part of the hemoglobin structure, decreases;
• Normocytic or normochromic anemia, which develops in chronic diseases, with a primary bone marrow failure, due to a decrease in the production of erythropoietin;
• Macrocytic anemia with a lack of cyanocobalamin and folic acid, when the size of red blood cells increases.

Each state needs its own treatment methods. To establish the diagnosis is very important clinical analysis of the blood, the interpretation of MCV (mean erythrocyte volume) allows you to judge the status of red blood cells.

If this indicator has normal values, the red blood cells are called normocytes. When the results of the MCV index are underestimated, the blood cells are called microcytial, and if they are overestimated, they are considered macro-cytoplasmic.

Determine the violation of water-electrolyte equilibrium in the body will allow MCV-analysis of blood, the interpretation of which indicates a change in the salt balance. If the average volume of red blood cells is less than normal, you can talk about the lack of fluid in the human body. For example, with dehydration of the hypertonic nature, MCV in the blood test is lowered. If this indicator is above the norm, then we can talk about dehydration hypotonic.

The results of MCV analysis can be influenced by various factors. Reduction of the average erythrocyte volume can cause a process of mechanical hemolysis or lead poisoning. Low MCV-analysis of blood, the interpretation of which indicates the alcoholism of the patient and the use of methanol as a poisonous substance, is also not uncommon.

MCV standard

The indicator of the mean erythrocyte volume depends on the age of the patient who passes the MCV blood test. The norm for each age group will be individual, and it is expressed in femtolitra. The standards set the range of this indicator, ranging from 80 to 100 femtoliters for adult patients.

In many cases, a very important MCV-analysis of blood, decoding. The norm is highest in newborn children. It should not exceed 140 femtoliters. As the child grows, the normal values of this indicator decrease. So, for a one-year-old baby the norm will be in the range of 71 to 84 femtoliters. From 1 year to 5 years of age, the mean volume of red blood cells varies from 73 to 85 femtoliters. Starting from 5 and up to 10 years the normal result is MCV analysis of 75 to 87 femtoliters, and only by the age of majority this indicator reaches the norm of an adult.

Underestimation of MCV

If MCV values in the blood test are lowered, this indicates the development of microcytic anemia. It develops when there is a shortage of iron ions in the blood plasma, the presence of chronic diseases and hereditary diseases, the development of malignant tumors, lead poisoning, the intake of certain medications, alcohol abuse, and thalassemia, when the synthesis of the polypeptide chain forming the hemoglobin structure decreases.

Overpriced MCV

Increased mean values of erythrocyte cells indicate the development of macrocytic anemia and other pathological conditions that are characterized by:

• Deficiency of B12 vitamin (cyanocobalamin) in case of impaired absorption;
• Folate deficiency anemia with a lack of folic acid;
• Megaloblastic anemia, caused by a violation of the synthesis of DNA molecules;
• Malignant anemia;
• Hypothyroidism, in which there is a shortage of thyroid hormones;
• Diseases of the intestine;
• Liver diseases;
• Decreased function of pancreatic cells;
• Diseases of red bone marrow;
• Toxic or drug poisoning;
• Alcoholism.

The MCV blood test may be slightly higher than normal when women take hormonal contraceptives. Smoking cigarettes can also cause an increase in the average volume of red blood cells.

The concept of MCH

Together with the definition of MCV, the MCH blood test allows differential diagnosis to determine the form of anemia. Means this indicator, how many on average in one erythrocyte Contains iron-containing hemoglobin protein. It is measured in absolute unit.

The average value of the hemoglobin content in one erythrocyte is calculated by dividing the concentration of hemoglobin by the number of erythrocyte cells. In comparison with the color index, MCH-analysis allows to more accurately determine the level of iron-containing protein in red blood cells.

Given the value of this index, anemia is distinguished for hyper-, hypo- and normochromic. Normochromia can be found in healthy people, but sometimes it accompanies hemolytic and aplastic anemia, as well as conditions associated with acute blood loss.

With hypochromia, there is a decrease in erythrocyte volume, called microcytosis, or a decrease in the content of the hemoglobin protein in erythrocytes with normal volume. Thus, a combination of hypochromia with both reduced size erythrocytes and normo- and macro-cytopids is possible.

The manifestation of hyperchromia occurs irrespective of the saturation of erythrocyte cells with hemoglobin protein and is due only to the volumes of red blood cells. This is due to the fact that as the hemoglobin content increases above the physiological norm, its crystallization and hemolysis of red blood cells occurs.