Mcv blood test deciphering the norm in women. What does the MCV indicator in the blood mean and what is its norm? What is mcv in blood tests

When making a diagnosis associated with diseases of the circulatory system, it is not always enough to determine the quantitative content of erythrocytes (red blood cells) and blood hemoglobin.

To obtain a detailed picture of the composition of the blood, the average volume of erythrocytes is measured - a more important and detailed hemolytic analyzer that characterizes the formed elements not from a quantitative, but from a qualitative side.

It is established by the ratio of the total volume of erythrocytes contained in a portion of blood to their number.

The result allows you to determine the average volume of one erythrocyte, which may be normal, and may be significantly lower or higher than normal.

Any deviation allows, in combination with other erythrocyte indices, to assume its own reasons leading to this, and to make a correct diagnosis.

This analysis is usually denoted by the abbreviation MCV, which, translated into Russian, means the average (Mean) corpuscular (Corpuscular) volume (Volume).

Units of measurement accepted in most laboratories: femtoliter (fl) or cubic micrometer (µm 3). It should be borne in mind that for some diseases this analysis is not reliable.

Limits of the norm by age categories

The indicator is called the norm if the values ​​​​of the average volume of erythrocytes appear in the range of not less than 80 and not more than 100 femtoliters. In newborns, the normal range is somewhat wider - from 70 to 110. With age, a person has a tendency to increase the indicator, from the minimum of the norm to the maximum, which is a physiological norm and does not require medical intervention.

MCV values ​​are independent of gender.

There are several erythrocyte characteristics in total:

The state of the blood will be called in such conditions normocytosis, microcytosis, macrocytosis or anisocytosis.

Macrocytosis, microcytosis and anisocytosis are accompanied by a certain pathology of the circulatory system, or a tendency to it. For example, the detection of a large number of microcytes indicates a lack of hemoglobin in the blood. Macrocytosis may indicate liver problems or hormonal disruptions.

When is MCV Analysis Necessary?

The doctor directs to determine the average volume of red blood cells for the following purposes:

• To give a deeper assessment of developing anemia;
• Detect metabolic disorders;
• Determine the degree of violation of the water and electrolyte balance in the patient;
• To adjust the treatment of severe pathologies.

This analysis is only an auxiliary method that sheds light on the nature of disorders in the body.

The reliability of this method in identifying various types of anemia or violations of water and electrolyte balance is beyond doubt.

So, hypertonic overhydration in most cases is accompanied by macrocytosis, and in hypotensive patients, indicators of microcytosis are recorded.

The MCV indicator, along with other 20 indicators, is included in the general analysis, for which capillary blood is taken from the finger. To prevent measurement errors, it is recommended not to eat before analysis.

In what diseases of the blood can the analysis be within the normal range?

Often, with severe anemia associated with a deficiency in the formation of hemoglobin, the volume of red blood cells may be within the normal range.

This is observed in the following situations:

When the average volume is lowered: what does it mean?

If the MCV in the blood test is below normal, then this indicates one of two situations:

• Erythrocytes, the main function of which is the transportation of hemoglobin through the tissues of the body, contain an insufficient amount of it;
• For some reason, there is an intensive destruction of already mature red blood cells.

These conditions, in which a low MCV is typical for:

If a child's blood count is reduced to 75 fl, then he is diagnosed with microcytic anemia.

When the mean volume of erythrocytes is increased

The 115 ft rise is typical for the following situations:

What does anisocytosis mean?

If red blood cells of different sizes are found in the blood - both micro- and macrocytes, then to characterize them, the distribution by volume of red blood cells is determined, which is denoted by the abbreviation RDW.

It is measured using a hemolytic analyzer that differentiates middle cells and determines the heterogeneity of red blood cells, that is, the deviation from the standard volume, and is expressed as a percentage.

Norm RDW - 11.5-14%. For proper differentiation of anemia and other pathologies, RDW measurement is always carried out in conjunction with MCV measurement.

With these measurements, the following regularities were revealed:

• A low MCV with a normal RDW indicates blood transfusion, thalassemia, and a removed spleen.
• With elevated MCV and normal RDW, liver pathologies are observed.
• If MCV is low and RDW is high, iron deficiency, beta thalassemia, or RBC sludge is suspected.
• If both indicators are elevated, then vitamin B12 deficiency, the effects of chemotherapy, or cold agglutination are assumed.

It is characteristic that in all the violations of blood structures presented, one of the most significant causes is a deficiency in the body of vitamin B12, and this is not accidental.

This vitamin is the most important factor in hematopoiesis, since only in its presence can bone marrow stem cells differentiate towards oxygen carriers, that is, erythrocytes.

And even if all other necessary elements of erythrocyte synthesis are present, with a lack of B12, the hematopoietic chain will break.

This main blood vitamin comes to us both from the outside, with food, and is synthesized in large quantities in the large intestine through the vital activity of beneficial microflora (bifidus and lactobacilli).

Therefore, in order to prevent violations of the hematopoietic function, to prevent a reduced amount of this element in food, to monitor the health of the intestines and rational nutrition is a paramount task.

The MCV indicator alone should not be trusted without supporting it with indicators of other erythrocyte indices. For example, the average volume of red blood cells will not be accurate if abnormally shaped bodies are found in the blood.

Only an integrated approach to assessing blood parameters will allow the doctor to identify the beginning pathology in a timely and qualified manner and determine the diagnosis as accurately as possible.

Video: Red blood cells. Volume.

Erythrocytes are blood cells that give the blood a red color due to the iron they contain. They carry hemoglobin to the tissues of all organs and remove carbon dioxide from them. The characteristics of red blood cells can tell about possible disorders in the field of hematopoiesis, oxygen saturation of the body, and bone marrow functionality.

The normal shape of an erythrocyte is a biconcave disc.

The value of the average volume is one of the most common in the analysis of blood. It can be calculated both during routine diagnostics and to identify possible anemia and its causes.

There are red blood cells of various sizes in the bloodstream, but most of them should be of a normal, correct size. This suggests that the cells are able to perform their functions optimally. Under the pressure of various factors, the percentage of abnormally large or small volumes can increase significantly. An analysis of the average volume will show which cell sizes predominate and allow you to prescribe a treatment regimen.

Normal values ​​by age

In the neonatal period, large erythrocytes predominate

Mean red blood cell volume (MCV) varies with age. In newborns, larger blood cells predominate, gradually their volume decreases, approaching those of adults.

How to Determine Mean Red Cell Volume (MCV)

The average volume of an erythrocyte is determined by a general blood test

The average volume of erythrocytes is diagnosed on the basis of a general clinical blood test. Special preparation for the analysis is not required, but it is recommended not to eat 4 hours before the blood sample is taken, and to exclude alcohol the day before. A hematology analyzer helps to determine the exact size of a blood cell, which allows you to reduce the percentage of test errors to almost zero.

Mean Cell Volume (MCV) is calculated using the formula:

MCV = HCT / RBC,

HCT is the total volume of red blood cells in a patient's blood unit (hematocrit);
RBC is the total number of red blood cells in 1 microliter of blood;
fl (femtoliter) - a unit of measurement of the average volume of an erythrocyte.

For example, if Hct = 41% and RBC = 4.54 ppm (4,540,000/µl), then:
MCV = 0.41 / 4,540,000 = 9.03 * 10^-15 = 90.3 fl.

What is anisocytosis?

Anisocytosis on a blood smear

Red blood cells are disc-shaped blood cells that can contract and bend to move through the thinnest capillaries. When their size exceeds the norm, they can no longer deliver oxygen to all tissues, when the size is smaller than usual, oxygen is delivered, respectively, less. Depending on the size, they are divided into 4 groups:

• microcytes -< 6,2 мкм;
• normocytes - 6.2 - 8.2 microns;
• macrocytes - 8.2 - 12 microns;
• megalocytes -> 12 microns.

In this case, normocytes, that is, cells of the correct size, should be about 70% of the total number of red blood cells. About 15% separate cells of large and small sizes. When an increase in the ratio of cells of abnormal size to normal is diagnosed in the patient's blood, anisocytosis is detected.

Anisocytosis is the general name for a high number of cells that are different in size from normocytes. There are 3 types of anisocytosis:

• microcytosis - the predominance of microcytes;
• macrocytosis - the predominance of macrocytes;
• mixed - both large and small cells exceed the allowable ratio.

The level of distribution of blood cells of the wrong size is recorded in the analysis by the RDW value. The RDW norm (in%) is:

• for adults - 11.5 - 14.5;
• for newborns - 14.9 - 18.7;
• for children from 6 months - 11.6 - 14.8.

Causes of deviation from the norm

Splenic dysfunction may cause anisocytosis

The results of the tests can be affected by the use of various medications, especially antidepressants, as well as the use of alcohol. If the factors contributing to the error in the results are excluded, and the indicators deviate from the norm, it is necessary to look for the cause. Factors causing deviations:

Erythrocyte indices correlate with each other

The MCV index correlates with other indexes for an accurate assessment of the condition of red blood cells. The definition of several characteristics at once allows you to understand the form of the disease, most often used to separate anemia according to their etiology. Above we talked about such values ​​as: RBC, HCT, MCV and RDW. A complete examination of red blood cells suggests additional values.

MCH - erythrocyte index, calculated by dividing total hemoglobin by the number of erythrocytes in the blood volume: MCH = HGB / RBC. The index value reflects the average content of hemoglobin in the erythrocyte. Some diseases, such as anemia with hyperchromia, are accompanied by an increase in MCH and MCV.

MCHC is an index indicating the concentration of hemoglobin in the mass of red blood cells. Unlike MSN, it determines not the quantity, but the density of hemoglobin filling of erythrocytes. It is calculated by dividing total hemoglobin by hematocrit: MCHC = HBG / HCT * 100. High MCV and low MCHC will indicate a disproportionate saturation of red blood cells with hemoglobin due to their abnormally large volume.

Not always the presence of the disease is reflected by a shift from the norm at once in all indicators. The practice of diagnosing shows that for various pathologies, one of the values ​​\u200b\u200bmay be normal, while the other indicates a disease. Moreover, it is the presence of a difference in the combination of indicators that is the reason for the diagnosis of certain diseases.

For example, with anemia caused by impaired hemoglobin synthesis, the RDW will be within the normal range, and the MCV will be lowered. Liver damage is reflected as normal RDW but elevated MCV.

MCV correction

Determining the cause is the first step in resolving the issue

Anisocytosis is formed as a result of negative factors that provoked an increase in the ratio of macrocytes or microcytes in the total number of red blood cells. Therefore, initially it is necessary to establish the cause of anisocytosis. In the absence of MCV correction, anemia of various types and forms develops, which leads to oxygen starvation of all organs.

If the reason lies in intoxication with chemicals, drugs, alcohol, the first thing to do is to exclude them. Additionally, antioxidant therapy may be prescribed.

Chronic infections that caused anisocytosis require complex treatment based on antiviral or antibacterial drugs.

A common cause is a deficiency of iron or vitamins of group B. The main factor in the correction will be the optimization of the content of trace elements in food, a course of vitamins and iron-containing preparations can be prescribed.

Restoring the normal state and ratio of red blood cells is not only drugs. Daily stress, bad habits, unhealthy diet cause the risk of anisocytosis. By adjusting your lifestyle, you will help your blood cells always perform their functions at the proper level.

Each of the numerous indicators in the decoding of a clinical blood test is diagnostically significant. Together, they reflect the characteristics of blood cells and their proportion in the patient's body. The MCV value in a blood test is an erythrocyte index that determines the average volume of cells responsible for oxygen transport in the human body.

The designation MCV is an abbreviation of the English term mean cell volume (literally, "mean volume of red blood cells"). The volume of a blood cell determines how much oxygen it can carry to the tissues. Erythrocytes of a smaller or larger volume, as well as a distorted shape, make it difficult to transport the necessary gas and can provoke hypoxia in the internal organs.

The MCV value in a blood test is important in diagnosing pathologies of the hematopoietic system, as well as an indirect indicator of autoimmune disorders, severe damage to the liver, thyroid and pancreas.

The value of the erythrocyte index is indicated in cubic micrometers (µm3) or femtoliters (fl). It is calculated theoretically, without measurements of cell sizes in the sample. This is due to the fact that the calculation error through the indicator of the diameter of red blood cells is much higher than that of the accepted method. To find MCV, the hematocrit number (total volume of red blood cells), indicated in the decoding of the analysis as HCT, is divided by the number of these cells.

Blood cells with a reduced volume compared to the norm are called microcytic, with an increased volume - macrocytic. A high error in the final result can occur only if erythrocytes are found in the blood with a distortion in both the smaller and the larger sides.

Preparation and conduct of the study

The study of the average volume of erythrocytes can be carried out in the order of a general blood test or separately from it. As a rule, the determination of only MCV is carried out with anemia or monitoring the course of its treatment.

The rules for taking biomaterial for analysis for the average volume of erythrocytes practically do not differ from the standard reminder for other blood tests. Before the procedure, the patient must adhere to the following recommendations:

1. Refrain from eating and drinking for at least 4 hours before blood sampling.
2. Do not take the test during menstruation.
3. Do research in the morning. Before taking blood, you need to calm down and rest from any physical activity for at least 20 minutes.
4. Tell the laboratory assistant or the attending physician in advance about the medications you are taking (some of them can affect the MCV).

At the same time, a number of points require stricter compliance, in particular, the absence of food and drink for 4-8 hours before the study. The intake of liquids or caffeinated beverages significantly affects the hematocrit index, from which the MCV is calculated.

In critical conditions (coma, cardiac shock), the average volume of erythrocytes is not determined.

Deciphering the results

Analyzing the results, the doctor focuses on the average indicators of a healthy person of the same age group as the patient. In babies, the MCV value can reach up to 140 fl, while the norm for an adult is almost 1.5 times less.

In adolescent boys, the average volume of erythrocytes is 1–2 units higher. However, after puberty, the situation is diametrically opposed: a difference of 2–3 μm3 is in favor of female patients.

MCV value (age norms)

In children under 10 years of age, the MCV can sometimes change for no reason and unpredictably. Deviations at this age do not have a decisive diagnostic value.

What do high values ​​mean?

If the value of MCV in the decoding of the blood test is increased, this indicates the development of macrocytic anemia. This condition can be caused by the following reasons:

• dysfunction of the thyroid gland;
• pathologies of the liver or pancreas;
• bone marrow neoplasia;
• food or drug poisoning;
• autoimmune diseases;
• alcoholism;
• bowel diseases;
• long-term use of combined oral contraceptives;
• smoking;
• poor ecology of the region of residence, work in hazardous industries.

At risk are also people with a hereditary predisposition to macrocytic anemia, men over 55 with bad habits, as well as patients with insufficient physical activity and an unbalanced diet.

Indirect external symptoms of macrocytic anemia are pallor of the lips, discomfort and pain in the abdomen, palpitations, and a yellow tint of the skin.

In the absence of adequate therapy, this condition can lead to a decrease in hemoglobin levels and a sharp deterioration in well-being.

What do low values ​​mean?

The result is less than the norm is also not a safe indicator. It may indicate conditions such as:

• Iron-deficiency anemia;
• thalassemia;
• peripheral disorder;
• malignant neoplasia in various organs and systems of the body;
• lead poisoning;
• dehydration (including while taking diuretics);
• pregnancy (due to increased iron intake).

The hereditary factor also affects the final value.

Signs of microcytic anemia are irritability, anxiety, low stress resistance, chronic fatigue, a sharp deterioration in memory, and an inability to concentrate.

The lack of treatment of the causes of this condition quickly leads to hypoxia of the internal organs and a decrease in the quality of life of the patient.

MCV is an important indicator for determining various diseases. Non-compliance with the norm may indicate pathologies, the treatment of which must be started as soon as possible. Therefore, one should not delay taking a corrective medication course or further diagnosis of the causes of micro- or macrocytic anemia.

MCV (from the English mean corpuscular volume) is one of the erythrocyte indices, which shows the average volume of erythrocytes. This indicator is able to characterize the entire population of erythrocytes in the blood. The calculated measure indicates the average volume that one erythrocyte occupies. The value of this index is calculated by the formula: hematocrit in percent, multiplied by 10 and divided by the total number of red blood cells in the blood. In most laboratories, MCV is measured in cubic microns (µm2) or femtoliters (fl).

A change in the erythrocyte composition of the blood is one of the main laboratory criteria in the diagnosis of anemia, therefore, the calculation of the average volume of erythrocytes in combination with other indicators of a clinical blood test is used for differential diagnosis, monitoring and evaluating the effectiveness of the treatment of anemia and diseases of the hematopoietic system, determining water and electrolyte imbalance.

MCV in a blood test is calculated automatically using a hematology analyzer, which determines the average value of the volume of all measured erythrocytes.

Red blood cells and their function in the body

Erythrocytes are red blood cells containing hemoglobin. Their main function is the transport of oxygen and carbon monoxide between the lungs and tissues of other organs. In addition, erythrocytes are involved in immune system reactions, play a significant role in maintaining acid-base balance, serve as a means of transporting nutrients (glucose, amino acids, salts, fatty acids) and decay products (uric acid, urea, ammonia, creatine).

Red blood cells are produced in the bone marrow. Their life cycle is 120 days, after its completion, erythrocytes are metabolized by cells of the liver, spleen and bone marrow. They are replaced by young forms of red blood cells called reticulocytes. Before entering the microvasculature, cells go through several stages of development, during which their shape, size and chemical composition change. For the normal synthesis of red blood cells, sufficient intake of vitamin B12, iron and folic acid is necessary.

Mature erythrocytes are non-nucleated cells that have the shape of biconcave discs, which allows them to penetrate into the narrowest and most curved sections of the vascular bed. Due to the plasticity of erythrocytes, the viscosity of blood in small capillaries is much less than in large ones.

The average diameter of a red blood cell in an adult is between 6.8 and 7.5 microns. Red blood cells with a diameter of less than 6.8 microns are called microcytes, and a condition in which the size of peripheral blood red blood cells is significantly smaller than normal means the presence of microcytosis. The presence in the blood of abnormally large, with a diameter of more than 8 microns, erythrocytes (macrocytes) makes it possible to suspect macrocytosis in a patient.

The determination of the erythrocyte index is performed as part of a general blood test, however, it can also be prescribed as a separate study.

The indicator of the average volume of erythrocytes has a diagnostic value in assessing micro- and macrocytosis, it is used in calculating the average content and concentration of hemoglobin in erythrocytes.

Normal MCV values

The norm of the MCV indicator in the blood test varies depending on age: in newborns it is maximum, in children in the first days and months of life its range is somewhat wider than in adults, after a year the indicator decreases, and by the age of 18 it is fixed at a level of 80 to 100 fl. This means that with age, the level of the average volume of erythrocytes becomes lower. In men and women, the MCV norm and the interpretation of the blood test will also be different. In addition, the norms of blood parameters may vary depending on the method of determination, laboratory, units of measurement.

Normal MCV values ​​by gender and age

An increase or decrease in the MCV in the general blood test may indicate various diseases and pathological conditions, for example, a violation of the water-salt balance: with a decrease in the average volume of erythrocytes, the violations are hypertonic in nature, and with an increase - hypotonic.

The average volume of red blood cells often decreases during pregnancy in women who are iron deficient.

Reasons for an increase in MCV

An increase in MCV in the blood may indicate a lack of vitamin B12, a lack of folic acid, the development of hyperchromic or macrocytic anemia, myelodysplastic syndrome, pathologies of the liver, bone marrow, renal failure, myxedema, hypothyroidism. The indicator of the average volume of erythrocytes can be increased in case of methanol poisoning, alcohol abuse, smoking, taking certain medications.

A false increase in the mean volume of erythrocytes can occur with hyperglycemia and diabetic ketoacidosis, cold agglutination of erythrocytes.

MCV in the blood test is low

The MCV indicator can be lowered in the case of microcytic anemia (iron deficiency, sideroblastic), hypochromic anemia with a lack of hemoglobin, thalassemia, in renal diseases that increase the level of erythropoietin, hypertensive dehydration, blood loss, conditions accompanied by a violation of the formation or increased destruction of red blood cells, liver diseases associated with tissue changes, erythremia, hypothyroidism, oncological and autoimmune diseases. The average volume of red blood cells often decreases during pregnancy in women who are iron deficient. The reason for the low rate may be lead poisoning, mechanical hemolysis, the presence of giant platelets.

To confirm or refute the diagnosis, additional studies are prescribed: biochemical blood test, determination of hormone levels, detection of tumor markers, immunological tests, ultrasound and others.

How is an MCV blood test done?

The determination of the erythrocyte index is performed as part of a general blood test, however, it can also be prescribed as a separate study.

The value of the MCV index is calculated by the formula: hematocrit in percent, multiplied by 10 and divided by the total number of red blood cells in the blood.

Blood sampling is performed on an empty stomach, after a night fasting period of at least eight, and preferably ten to twelve hours. On the eve of the analysis, it is recommended to refrain from excessive physical and psycho-emotional stress, to exclude physiotherapeutic procedures.

MCV in a blood test is calculated automatically using a hematology analyzer, which determines the average value of the volume of all measured erythrocytes. The method of manual calculation, in which the laboratory assistant himself counts the cells and makes calculations according to the formula, is rarely used.

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It allows you to determine the quantitative and qualitative composition, which in turn indicates the state of human health and the presence of any problems. In addition to leukocytes and platelets, erythrocytes are subjected to a thorough study. These red blood cells perform a transport function, delivering nutrients and oxygen to all cells and organs. One of the indicators of their level is the erythrocyte index, denoted MCV. This index allows you to estimate the number and size of red blood cells, which in turn is associated with the general condition of the body. What else does MCV say in a blood test, what is it and what norm indicators are established, we will find out further.

Erythrocyte index MCV shows the total volume of red blood cells contained in the blood. In a healthy person, this coefficient is a constant value, the change of which entails pathological changes in the body.

Allocate two main indicators that determine the need for analysis:

1. Determination of violations of the water-salt balance (in case of intestinal infections, acute respiratory infections and acute respiratory viral infections).
2. Diagnosis of anemia (iron deficiency).

Also indications for research may be manifestations such as:

• hormonal disruptions;
• metabolic disease;
• obesity;
• diabetes;
• low immunity.

Most often, MCV analysis reveals various forms of anemia:

• normochromic anemia - develops with pathologies of the bone marrow, which are caused by the presence of chronic diseases;
• macrocytic anemia - a pathological increase in red blood cells in size due to a lack of B vitamins and folic acid;
• microcytic anemia - develops as a result of acute iron deficiency, resulting in a decrease in the synthesis of polypeptide chains.

In a healthy person, the normal MCV is from 80 to 100 femtoliters. This indicator is a nomrocyte, which means full compliance with the established norm. Exceeding values ​​of more than 100 femtoliters is a macrocyte, and a decrease of less than 80 is a microcyte.

Units of measurement and calculation

The average volume of an erythrocyte is calculated in femtoliters or cubic micrometers. This erythrocyte index is determined using a mathematical formula that displays the ratio of hematocrit as a percentage to the total number of erythrocytes, after which the resulting value is multiplied by 1012 liters.

How is the analysis carried out?

In medical practice, MCV can be included in a complete blood count, or be performed without taking into account other blood fractions. For analysis, you will need blood from a finger or a vein, taken in accordance with all the rules:

• the patient does not eat or drink 3-5 hours before blood sampling;
• women do not have menstruation;
• the person feels satisfactorily (no coma and cardiological shock).