Counting the number of red blood cells, determining their average volume or in a blood test in combination with other studies are used to conduct differential diagnosis of various forms of anemia and other pathological conditions.
What are red blood cells
According to the characteristics of red blood cells (red blood cells), which are highly specialized nuclear-free blood cells of a biconcave form, one can judge the state of human health. Red blood cells contain a respiratory pigment - an iron-containing hemoglobin protein.
The main
function of red blood cells is oxygen transfer, which is very important for the functioning of all organs in the body.
Red bone marrow is responsible for the formation of these cells
. 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 supply of iron ions. Red blood cells in the systemic circulation last about 4 months. Then there is the destruction of blood cells, the place for their decay is the spleen and reticuloendothelial system.
What does MCV mean?
MCV is an erythrocyte index that characterizes the value of the average volume of red blood cells. To establish an accurate diagnosis of the disease, doctors always prescribe a clinical blood test for patients. Decoding MCV indicates the state of blood cells in the human body. In healthy people, the ratio of red blood cells to total blood volume is constant, which means that their size and quantity should not change.
You can learn about the development of allergies, inflammatory processes, and the lack of vitamins and minerals by taking an MCV blood test. An interpretation of its results, showing deviations from the norm, indicates possible pathological conditions.
This indicator is determined both during a general clinical blood test, and as a separate study.
How to calculate MCV
To calculate the average erythrocyte volume, it is necessary to divide the sum of the cell volumes by the total number of red blood cells. Another method of calculation is based on dividing the hematocrit index or number for 1 mm 3 of blood by the number of all red blood cells. By hematocrit number is meant the percentage of blood cell volume and total blood volume.
On the MCV, a blood test, the decoding of which is associated with an estimate of the size of red blood cells, is considered less accurate compared to the other two calculation methods. This is due to the fact that when the diameter of the red blood cell changes by 5%, its volume changes by 15%. The reliability of this indicator may be distorted when there is a large number of red blood cells in which the shape is changed. For example, if a general blood test is performed , the MCV value will be normal if the patient has both macro- and microcytosis.
It should be borne in mind that the diameter of microspherocytes is usually underestimated, but the average volume indicator is within normal limits, which is why microscopy of a blood smear is always recommended.
unit of measurement
Femtoliters (fl) or cubic micrometers (ΞΌm 3 ) were taken as a unit of measurement of mean red blood cell volume (MCV).
What does the analysis show?
Using this blood indicator, various types of anemia are diagnosed that require specific treatment.
MCV results in a blood test distinguish between:
- 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 primary bone marrow failure, due to a decrease in erythropoietin production;
- macrocytic anemia with a lack of cyanocobalamin and folic acid, when the size of red blood cells increases.
Each condition needs its own treatment methods. To establish a diagnosis, a clinical blood test is very important, decoding MCV (average red blood cell volume) allows you to judge the state of red blood cells.
If this indicator has normal values, then red blood cells are called normocytic. With underestimated results of the MCV index, blood cells are called microcytic, and with overestimated values ββthey are considered macrocytic.
MCV-analysis of blood will allow to determine the disturbance of water-electrolyte balance in the body, the interpretation of the indicators of which indicates a change in the salt balance. If the average volume of red blood cells is less than normal, we can talk about a lack of fluid in the human body. For example, with dehydration of a hypertonic nature, MCV in a blood test is lowered. If this indicator is higher than normal, then we can talk about hypotonic dehydration.
Various factors can influence the results of MCV analysis. Reducing the average red blood cell volume can cause mechanical hemolysis or lead poisoning. A low MCV blood test, the interpretation of which indicates the patient's alcoholism and the use of methanol as a toxic substance, is also not uncommon.
Norm MCV
The average red blood cell count depends on the age of the patient who is taking the MCV blood test. The norm for each age group will be individual, and it is expressed in femtoliters. The standards set the range of this indicator, ranging from 80 to 100 femtoliters for adult patients.
In many cases, an MCV blood test, transcript, is very important. The norm is highest in newborns. It should not exceed 140 femtoliters. As the child grows, the normal values ββof this indicator decrease. So, for a one-year-old baby, the norm will be in the range from 71 to 84 femtoliters. From 1 year to five years of age, the value of the average volume of red blood cells ranges from 73 to 85 femtoliters. From 5 to 10 years, the result of MCV analysis from 75 to 87 femtoliters is considered normal, and only by adulthood this indicator reaches the norm of an adult.
Undervalued MCV
If the MCV values ββin the blood test are lowered, this indicates the development of microcytic anemia. It develops with a lack of iron ions in the blood plasma, the presence of diseases of a chronic nature and hereditary diseases, the development of malignant tumors, poisoning with lead compounds, taking certain medications, alcohol abuse, with thalassemia, when the synthesis of the polypeptide chain, which is part of the hemoglobin structure, decreases.
Overvalued MCV
Increased values ββof the average volume of red blood cells indicate the development of macrocytic anemia and other pathological conditions that are characterized by:
- deficiency of B 12 vitamin (cyanocobalamin) with malabsorption;
- folic acid deficiency anemia with a lack of folic acid;
- megaloblastic anemia due to a violation of the synthesis of DNA molecules;
- pernicious anemia;
- hypothyroidism, in which there is a lack of thyroid hormones;
- bowel diseases;
- liver diseases
- decreased pancreatic cell function;
- diseases of the red bone marrow;
- toxic or drug poisoning;
- alcoholism.
The MCV of a blood test may be slightly higher than normal when women take hormonal contraceptives. Cigarette smoking can also cause an increase in the average volume of red blood cells.
The concept of MCH
Together with the definition of MCV, an MCH blood test allows differential diagnosis to determine the form of anemia. This indicator means how much is on average in one red blood cell contains iron-containing hemoglobin protein. Measured in absolute unit.
The average hemoglobin content in one red blood cell is calculated by dividing the hemoglobin concentration by the number of red blood cells. Compared with the color index, MCH analysis allows you to more accurately determine the level of iron-containing protein in red blood cells.
Given the value of this index, hyper-, hypo- and normochromic anemia are distinguished. 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 red blood cell volume, called microcytosis, or a decrease in the hemoglobin protein content in red blood cells with a normal volume. Thus, a combination of hypochromia with both reduced erythrocytes and normo and macrocytes is possible.
The manifestation of hyperchromia takes place regardless of the saturation of red blood cells with hemoglobin protein and is due only to the volume of red blood cells. This is due to the fact that with an increase in the hemoglobin content above the physiological norm, its crystallization and hemolysis of red blood cells occur.