Red blood cells in the blood: functions

Erythrocytes are the most numerous variety of human blood cells (every fourth cell of the body is an erythrocyte). Every second, several million red blood cells are destroyed in the human body. And the same amount is synthesized in the bone marrow to replenish the reserves of red blood cells in the vessels. These small but very important cells are not only vital for each of us, but they can also tell a lot about the state of health. Therefore, the study of the level of red blood cells (as part of a general clinical blood test) is an important diagnostic procedure that should be regularly performed by both adults and children.

Functions of red blood cells

The main function of erythrocytes is the transfer of oxygen, which is carried out thanks to hemoglobin — a special protein in their composition. In addition, red blood cells are involved in the transport of nutrients, immune reactions and help maintain acid-base balance.

Red blood cells are very small in size — one hundredth of a millimeter in diameter. These cells are like elastic discs with a recess in the middle, thanks to which they are able to twist, easily penetrating even the thinnest — thinner than a human hair — vessels of the body.

It’s interesting!

Human erythrocytes, like all mammals, do not have a nucleus. On this basis, they can be distinguished from the red blood cells of other animals — for example, birds or frogs, by examining a blood sample under a microscope.

Red blood cells are formed in the red bone marrow of a person. Before entering the vascular bed, cells go through several stages of development, during which they change shape, size and composition. Normally, in the analysis of blood taken from a finger or from a vein, there are no varieties of erythrocytes except mature cells (they are called normocytes) and young forms (reticulocytes). The content of the latter in the body of healthy people is about 1% .

The level of red blood cells in the blood of healthy people

Normally, the content of red cells in the blood of adult men is 4.3 × 10 12 – 5.7 × 10 12 cells / l. In women, this indicator is slightly less — 3,8 × 10 12 – 5,1 × 10 12 cells/l. As for children, the norms of red blood cells differ depending on the age of the child.

In the first two weeks, the content of red blood cells in the blood — 3,9 × 10 12 – 5,9 × 10 12 cells/l. The norm of red blood cells in a month-old baby — 3,5 × 10 12 – 5,1 × 10 12 cells/l. In two to four months — 3,6 × 10 12 – 4,8 × 10 12 cells/l. Up to six months — 3,8 × 10 12 – 4,6 × 10 12 cells/l. Up to a year — 3,9 × 10 12 – 4,7 × 10 12 cells / l (before this age, the norm for reticulocytes is 0.2–2.8%). From one year to nine years, the content of red blood cells ranges from 3.9 × 10 12 – 4.5 × 10 12 cells /l. The normal number of red blood cells in children under 12 years of age is approximately 4.2 × 10 12 – 4.6 × 10 12 cells / l, regardless of the sex of the child.

As the child grows up, the norms of red blood cells in the blood begin to differ depending on his gender. Thus, in adolescent girls aged 12-18, a healthy indicator is 3.8 × 10 12 – 5.1 × 10 12 cells / l. Boys 12-15 years old — 4,1 × 10 12 – 5,2 × 10 12 cells / l, and from 15 to 18 years — 4,2 × 10 12 – 5,6 × 10 12 cells/l. This is due to the peculiarities of the growth and development of boys and girls.

Compared with middle-aged people, the number of red blood cells in the blood of the elderly is gradually decreasing. The normal indicator is 3.8 × 10 12 – 5.3 × 10 12 for women and 3.8 × 10 12 – 5.8 × 10 12 for men.

Another category for which there is a separate standard is pregnant women. The fact is that during the intrauterine development of the child, the volume of circulating blood in the expectant mother increases due to the liquid part (plasma), while the number of shaped elements grows more slowly. Therefore, the norm for the content of erythrocytes in the blood of pregnant women is 3.5 × 10 12 – 5.6 × 10 12 cells / l. The number of reticulocytes during this period should not differ from normal values for an adult (about 1%).

Elevated red blood cells in the blood: causes of deviation

It would seem that the more red blood cells we have in our blood, the better. However, such a judgment is erroneous, because an excess of cells thickens the blood and violates its properties. In addition, erythrocytosis (as the increased content of red blood cells is called in medicine) is a sign of some serious diseases.

Symptoms of erythrocytosis:

  • dizziness;
  • nosebleeds;
  • frequent headaches;
  • there may be redness of the skin on the body.

Why are red blood cells elevated in the blood test?

The simplest and most common explanation is dehydration of the body, which is provoked not only by heat, but also by fever, vomiting, diarrhea (that is, precisely those symptoms that often become the reason for going to the hospital and passing a general blood test).

Other, less likely causes of erythrocytosis include tumors of the kidneys or endocrine glands, as well as an excess of steroid hormones in the body (they are prescribed for certain diseases). The content of red blood cells in the blood also increases in situations associated with a lack of oxygen: for example, if a person has recently returned from a hike in the mountains or if he suffers from lung diseases (such as COPD) and heart, in which the process of oxygen transport is disrupted. Such pathologies include chronic bronchitis, bronchial asthma and heart defects. Smoking can also cause a decrease in oxygen and, accordingly, an increase in the production of red blood cells.

It’s important to know!

Extremely rarely, the number of red blood cells in the blood increases due to a hereditary disease called true polycythemia (Vaquez disease). In fact, it is a type of blood cancer in which the bone marrow begins to produce too many cells. Vaquez’s disease occurs in one in 100,000 people, mainly in the elderly. It is impossible to cure it, but the fulfillment of doctor’s prescriptions allows patients with true polycythemia to suppress the manifestations of the disease for many years.

There are many possible reasons for the increase in reticulocytes. If the blood test was preceded by bleeding or anemia treatment, then reticulocytosis is a good sign that indicates the restoration of red blood cell reserves in the vascular bed. If there are no obvious reasons for the growth of reticulocytes, it is necessary to consult a hematologist: this situation may indicate a hereditary blood disease or a tumor.

Low red blood cell count: Causes

Erythropenia is a low content of red blood cells in the blood.

Signs of erythropenia:

  • weakness;
  • tinnitus;
  • rapid fatigue;
  • pronounced pallor of the skin.

Why are red blood cells lowered in the blood test?

  • Acute blood loss (in case of injury or during surgery).
  • Chronic blood loss (heavy menstruation in women or latent bleeding — with stomach or duodenal ulcer, hemorrhoids, intestinal cancer and other diseases).
  • Insufficient intake of iron into the body with food (it is necessary for the synthesis of hemoglobin).
  • Poor absorption or deficiency of vitamin B12 and folic acid in food.
  • Chronic insufficiency of kidney function, since it is in the kidneys that the hormone that stimulates the formation of red blood cells, erythropoietin, is synthesized.
  • Excessive fluid intake or the introduction of an excessive amount of saline intravenously through a dropper.
  • Too rapid destruction of red blood cells due to an error in blood transfusion, due to hereditary diseases (such as sickle cell anemia), poisoning with heavy metals or other poisons, as well as in patients with an artificial heart valve.

The content of reticulocytes in the blood is often reduced as a result of alcohol abuse (it worsens the functioning of the kidneys and bone marrow), with anemia and the presence of metastases of malignant tumors in the bone marrow.

Other pathologies of red blood cells

In addition to the quantitative content of red blood cells and reticulocytes in the blood, it is important to pay attention to other parameters of a detailed blood test related to the state of red blood cells. Here are the main ones:

The shape of red blood cells . In some pathologies, doctors notice a change in the appearance of cells. For example, due to Minkowski -Shoffar disease, ovalocytosis or sickle cell anemia, red blood cells instead of flattened become round (spherocytosis), oval (elliptocytosis) or acquire the shape of a sickle. In rare cases, small outgrowths of the same (acanthocytosis) or different (echiocytosis) sizes are found on the surface of cells. The cause of such changes is the pathology of the liver, stomach or genetic disorders.

Hemoglobin level . Hemoglobin is a pigment that is part of red blood cells, thanks to which gas exchange occurs in the body. The increase and decrease in its content in the blood is most often correlated with the number of red blood cells, but sometimes these indicators change independently of each other. Normal hemoglobin concentrations are 132-173 g/l for men, 117-155 g/l for women, 152-235 g/l for newborns, 90-166 g/l for monthly infants. The norm of hemoglobin in the blood of children from six months to 12 years is 110-140 g / l, and by adulthood these values are approaching “adult” indicators. In pregnant women, the hemoglobin level in the blood should be at least 110-140 g/l. Lack of hemoglobin is called anemia — this disease can be caused by a deficiency of iron or vitamins in the body, as well as acute or chronic blood loss. And the causes of increased hemoglobin in the blood, as a rule, coincide with the causes of erythropenia.

The rate of erythrocyte sedimentation (ESR) often increases with inflammatory processes in the body, and decreases with chronic circulatory disorders. Normally, ESR in men is 1-10 mm / h, in women 2-15 mm / h. In newborns, ESR should correspond to a value of 2-4 mm/ h, in babies under one year — 2-4 mm/ h, up to five years — 5-11 mm/ h, up to 14 years — 4-13 mm / h. After this age, ESR in children approaches “adult” indicators, taking into account gender. The rate of ESR in pregnant women increases every month, starting from the fourth. In the first trimester, it is 15 mm / h, in the second — 25 mm / h, in the third — 40 mm / h, and three months after delivery, its values return to the original ones.

Erythrocyte indices . Other parameters of the state of red blood cells are reflected in the indicators indicated in the analysis as erythrocyte indices. The most informative of them are MCV (average erythrocyte volume), MCH (average hemoglobin content in erythrocyte), MCHC (average hemoglobin concentration in erythrocyte mass) and RDW (coefficient of average erythrocyte volume). Deviations from the normal values of these indicators help the doctor to clarify the cause of anemia in the presence of deviations in the standard parameters of the blood test.

Despite the variety of blood parameters characterizing red blood cells, it makes no sense to remember the meaning of each of them and worry extremely about possible deviations in the absence of any symptoms. There are many physiological conditions that explain changes in erythrocyte parameters, which a competent doctor will be able to distinguish from pathology.

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