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Erythrocytes, or red blood cells, are the basic component of the blood that carries oxygen. Blood morphology, which is used, among other things, to assess them, is one of the most frequently performed laboratory tests. Thanks to it, you can find out what the norm of red blood cells is. What does it mean when there are too many red blood cells and what does it mean when there are too few red blood cells?

Erythrocytesi.e.red blood cells(Greekerythros -red,kytos- cell) were first described in the 17th century by the father of microbiology, the Dutch naturalist, Antoni van Leeuwenhoek.

Red blood cells, thanks to the content of hemoglobin, fulfill several important functions in our body, primarily they carry oxygen.

Our well-being and he alth depend on their condition, so it is worth checking them regularly, especially after the age of 50.

Structure of red blood cells

The red blood cell is a small (7.5 μm in diameter and about 2 μm in thickness), round cell, shaped like a biconcave disk in cross section.

This construction has several advantages:

  • increases the surface to volume ratio , making it easier to attach and release oxygen,
  • the distance of the centrally located hemoglobin from the cell surface is shorter, and thus its better use,
  • also the blood cellis more pliableto overcome constrictions and bends in the smallest blood vessels.

Erythrocytes contain a minimal amount of organelles, they lose their nucleus during maturation, they arenuclear-free , and mitochondria, centrioles and the Golgi apparatus also disappear.

This is to minimize its own metabolism, hence, the erythrocyte itself does not need a large amount of energy and obtains it from glycolysis, which is an anaerobic process carried out in the cytoplasm. As a result, it does not consume the oxygen it carries.

The absence of organelles does not mean that erythrocytes contain only cytoplasm. They are filled with hemoglobin - a red dye that contains an iron ion (Fe2 +) and binds oxygen reversibly.

Cellular skeleton made of spectrin and ankyrin as well as enzymes, e.g. glucose-6-phosphate dehydrogenase, are responsible for the shape of the blood cell.

In addition, this blood cell contains a lotother enzymes, and there are numerous membrane proteins on the surface, including blood group antigens (AB0 and Rh systems), which are glycoproteins.

It is the presence of these compounds and their system that determines the blood group of a person.

Functions of red blood cells

It is well known that erythrocytes are responsible forthe transport of oxygen from the lungs to the peripheral tissues , this role is due to the presence of hemoglobin.

It is hemoglobin that has the ability to unstable oxygen binding where there is a lot of it, i.e. in the lungs, and to return it where there is little - in other tissues.

The addition of oxygenis associated with the change in the degree of iron oxidation in hemoglobin from Fe2 + to Fe3 +, and the oxidized hemoglobin is calledoxyhemoglobin .

Giving up oxygenobviously causes the opposite reaction and returning the iron to the second stage (Fe2 +), and thus the readiness to reattach oxygen. The whole process takes place repeatedly.

Sometimes it happens that the erythrocyte will attach a substance other than oxygen, if it iscarbon monoxide , which has a much greater affinity for hemoglobin, oxygen is displaced from it, and the connection becomes irreversible.

As a result, the erythrocyte loses its ability to perform its function, and the resulting compound iscarboxyhemoglobin .

If, however, hemoglobin is exposed tooxidizing factor , such as drugs, it is also impossible to add oxygen, because iron with Fe2 + is permanently transformed into Fe3 +, which is not may be more oxidized.

This form of hemoglobin ismethemoglobin .

Both abnormal forms of hemoglobin can be treated, usuallywith high doses of pure oxygen , but there is only a chance of recovery if the amount in the circulation is low.

Another important task of erythrocytes is the regulation of blood pH - red cells are one of the basic buffers of blood.

A less important function of red blood cells is to carry carbon dioxide.

Hemoglobin only slightly transports carbon dioxide from the tissues to the lungs, this form of it is calledcarbaminohemoglobinand, like oxyhemoglobin, it is an unstable bond.

Most carbon dioxide is dissolved in plasma.

Production and breakdown of red blood cells

The erythrocyte production process iserythropoiesis , and the cells from which they arise -erythroblasts . Red blood cells are produced and matured in the red bone marrow, i.e. in the epiphyses of long bones and in flat bones.

What's interesting in fetal lifeErythrocytes are also produced in the spleen in the liver and in the yolk sac.

Onlymature forms are released into the bloodand a small percentage of immature - reticulocytes, if there are too many of them or there are earlier stages of development in the blood, we are dealing with a production disorder or too fast loss of blood cells from circulation, such a situation requires diagnostics.

Every minute, about 2.6 million red blood cells are formed.

A number of ingredients are needed for the proper production of blood cells:

  • primarily iron - erythrocytes contain up to 80% of iron present in the body, i.e. about 3.5 grams
  • vitamin B12
  • folic acid
  • vitamin C
  • vitamin B6
  • vitamin E

and this process is stimulated by erythropoietin secreted by the kidneys, they have less influence:

  • glucocorticosteroids
  • thyroid
  • adrenalina

Erythrocytes live for about 120 days, after which time they are captured by the liver and spleen, the latter acts as a filter removing old and abnormal blood cells.

The ingredients that make up erythrocytes are "recycled" - they are reprocessed and used to produce new blood cells.

Hemoglobin is metabolized in the liver to produce bilirubin, which gives bile its color. Then urobilinogen, stercobilin and urobilin are formed from bilirubin, the latter is the stool dye, and the last one is present in the urine giving it a yellow color.

The iron in the hemoglobin is mostly reused, only a small amount is excreted from the body.

Erythrocytes: norm

Blood morphologyof blood is a basic test, it is often performed not only in various diseases, but also in he althy people in order to assess the general condition of the body in a very basic way.

The result of this study contains several data, the correct interpretation of which says a lot about red blood cells - their structure, production process, and performance.

The important parameter isthe number of erythrocytes (RBC), normal values ​​vary :

  • from 4.2 million to 5.4 million blood cells / μl for men
  • 3.5 million cells / μl to 5.2 million cells / μl for women

The most important, however, isthe amount of hemoglobin (HGB or HB) its norms fluctuate :

  • 14 to 18 g / dl for men
  • 12 to 16 g / dL for women.

This parameter evaluates the amount of hemoglobin in a given blood volume and it is taken into account e.g. when making decisions aboutblood transfusions.

The next quantity ishematocrit(HT or HCT), it is the ratio of the erythrocyte volume to the volume of the whole blood sample, itsnormal values ​​are:

  • from 40% to 54% for men
  • 37% to 47% for women.

Erythrocytes above normal

The increase in the number of red blood cells iserythrocytosis(i.e.erythrocytes above normal ), its cause is most often dehydration, the increase is simply associated with blood thickening.

The cause of erythrocytosismay also be a long-term slight hypoxia of the body, it takes place in various situations:

  • being in high mountains, where oxygen in the air is much less
  • smoking cigarettes, it results in the presence of small amounts of carbon monoxide, some erythrocytes do not fulfill their function, and the body balances this state by producing additional blood cells
  • obstructive sleep apnea syndrome, this disease consists of interruptions in breathing and a lack of oxygen supply to the lungs
  • lung diseases (e.g. COPD), they reduce the efficiency of oxygen transfer from the lungs to the blood

Occasional causes of hyperaemia are:

  • congenital heart disease in which deoxygenated blood is mixed with oxygenated blood
  • drugs, e.g. glucocorticoids
  • polycythemia vera, i.e. an uncontrolled increase in the number of erythrocytes, is one of the rarest causes of the increase of these blood cells, and the RBC values ​​exceed the upper limit of normal several times

Erythrocytes below normal

Decreased red blood cell parameters areerythrocytopenia(i.e.erythrocytes below normal ) and indicate anemia, i.e. anemia.

There are many reasons for this, the most common is iron deficiency, then vitamin B12 and folic acid. This condition also occurs in the course of chronic diseases and after haemorrhage, and the rarest are haemolytic anemias (related to the destruction of blood cells).

Anemia can also be a sign of fluid overload and sometimes occurs during pregnancy.

It should be remembered that slight deviations in morphology may also occur in completely he althy people. However, it is worth consulting each result of this test with your doctor.

Erythrocytes and other morphology parameters

If anemia is found based on the number of erythrocytes, hemoglobin, and hematocrit, other morphological data will greatly assist in diagnosing the cause of the condition. These values ​​are:

  • average blood hemoglobin content (MCH), which is the mass of itthe compound contained in one erythrocyte, here the norm is in the range 27-31 pg
  • the mean concentration of hemoglobin in the blood cell (MCHC), i.e. the mass of hemoglobin in a given volume of erythrocytes, the norm is 32-36 g / dl

If these values ​​are lowered, iron deficiency anemia is the main suspect, but it can also be caused by chronic diseases or thalassemia.

The increase in MCH and MCHC can be observed in spherocytosis, i.e. a disease in which red blood cells have an abnormal shape. The next parameter is:

  • average blood cell volume (MCV), or simply its size, should be in the range 82-92fl.

A reduction in MCV confirms a diagnosis of iron deficiency anemia, but it also occurs, although much less frequently, in thalassemia and chronic diseases.

Increase in this parameter can be observed in anemia caused by vitamin B12 and folic acid deficiency, the lack of these micronutrients may be caused by a lack of diet, stomach and intestinal diseases, but also liver cirrhosis and alcoholism.

MCV also increases in hypothyroidism and as a result of chemotherapy and sometimes during pregnancy.

Less important in the overall assessment are two parameters:

  • reticulocytes (Ret.) , their norm is 0.5-1.5% of the amount of erythrocytes, and in absolute amounts 20-100 thousand / μl. These are juvenile, immature forms of red blood cells that have just left the bone marrow. Their presence is associated with replenishing the missing pool of erythrocytes, which are physiologically destroyed. The increase indicates the compensation of excess blood cells, it occurs in the case of: haemolytic anemia, haemorrhage, and also after the proper treatment of anemia. A decrease is observed when the process of erythrocyte production is disturbed, i.e. in aplastic anemia and vitamin B12 deficiency anemia. It is a very accurate indicator of the correctness of the blood cell production process
  • coefficient of variation of the red blood cell volume distribution (RDW-CV) , the norm is 11.5-14.5%, simply speaking, this figure determines how much the individual sizes differ from each other Red blood cells. Results above 14.5% may occur as a result of deficiencies - iron, vitamin B12, or folic acid, as well as after blood transfusion.

If laboratory tests do not give a decision as to the cause of the disturbances in the number or structure of red blood cells, a bone marrow biopsy is performed and the process of production of these blood cells is assessed.

Erythrogram, optical evaluation of blood cells

Currently, all blood analysis is performed onusing automatic analyzers, but the words describing the appearance of erythrocytes still exist, they are used, for example, to accurately describe the nature of anemia.

In terms of size we have:

  • microcytes- small red cells
  • macrocytes- large red blood cells
  • megalocytes- giant red blood cells

If, however, we relate these concepts to the parameters described above, it can be concluded that they correspond to the MCV, i.e. the erythrocyte volume.

Anisocytosis is the presence of erythrocytes of various sizes in the circulation.

In terms of incorrect shape, we can distinguish:

  • spherocytes- round erythrocytes
  • leptocytes- thin erythrocytes
  • ovalocytes- oval erythrocytes
  • acanthocytesandechinocytes- erythrocytes with projections
  • schizocytes- fragments of red blood cells
  • thyroid erythrocytes

The phenomenon of different shapes of erythrocytes is called poikilocytosis, and each of the above-mentioned appearance of blood cells is characteristic of a disease in which such erythrocytes occur, e.g. schizocyte in microangiopathic anemia and leptocyte in thalassemia.

Also the color of erythrocytes has appropriate terms describing it:

  • hypochromia- weaker pigmentation with increased central brightness
  • hyperchromia- strong coloration and no brightening inside
  • polychromatophilia- heterogeneous color of one blood cell
  • anisochromiabut it is the simultaneous occurrence of blood cells staining correctly and incorrectly

The color of the erythrocyte is related to the hemoglobin content, i.e. MCH and MCHC, and these values ​​indirectly determine their appearance.

It is also worth knowing about a few other abnormalities that may affect red blood cells:

  • erythroblastsare immature erythrocytes containing a cell nucleus, they appear in the circulation in the case of increased production of erythrocytes or in the course of blood cancers
  • blood cells rolltakes place when they are coated with antibodies
  • Howell-Jolly bodiesare remains of the cell nucleus, they can sometimes be observed in anemia
  • Heinz bodiesis damaged hemoglobin, occurs in thalassemia and methemoglobinemia
  • Howell-Jolly and Heinz bodiesare collectively referred to as intra-erythrocyte inclusions
  • Hyperemia (polycythemia):causes, symptoms and treatment
  • Blood diseases: anemia, polycythemia, leukemia, hemophilia
Important

Blood morphology is a simple, widely available test that assesses not only erythrocytes, but also leukocytes and platelets.

Interpretation should be left to the physician, however, as proper evaluation of the result requires knowledge and experience.

Single, slight deviations are usually not a cause for concern, and abnormalities in the blood count should be verified by repeating the test.

The method of preparation for the examination is extremely important, i.e. you cannot exercise or stand for a long time before the examination. You should also fast for 8 hours before the test.

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