Why are reticulocytes in the blood

Reticulocytes are an important indicator of bone marrow regenerative capacity. Increase them in peripheral blood ( reticulocytosis ) it is noted in hemolytic anemias, when their number can reach up to 60% or more (increasing especially during hemolytic crises), in acute blood loss (3–5 days after hemorrhage a reticulocytic crisis occurs), malaria, polycythemia, during iron treatment of iron deficiency anemias , a few days (3-10) after the start of anti-anemic treatment of pernicious anemia, with acute lack of oxygen. The presence of an increased number of reticulocytes makes it possible to suspect latent bleeding (for example, in patients with typhoid fever, peptic ulcer).

It is believed that an increase in the number of reticulocytes in peripheral blood is an expression of good regeneration only if there is reticulocytosis at the same time and in the bone marrow, what is calledtruereticulocytosis . The absence of an increased number of reticulocytes in the bone marrow with an increase in their number in the peripheral blood indicates an increase in the leaching of reticulocytes from the bone marrow into the peripheral blood (falsereticulocytosis ).

Reticulocytosis, without a corresponding erythromoborblastic reaction of the bone marrow, is observed when some areas are irritated by its cancer metastasis or inflammatory foci.


Decrease in the number or absence of reticulocytes ( reticulocytopenia ) Observed at aregeneratornyh aplastic and hypoplastic anemia, anemia caused by iron deficiency, vitamin B12, folic acid (microcytic, hypochromic and megaloblastic anemia), thalassemia, sideroblastic anemia, metastases of cancer to bone, radiation sickness, radiation therapy, treatment with cytostatics.

Erythrocyte anisocytosis, types, causes of development.

Anisocytosis is the process by which the size of a blood cell changes. Anisocytosis is a laboratory term for a significant or moderate change in the metric parameters of blood cells, which is a reflection of the development of pathological conditions or is observed as a physiological compensatory mechanism.

A change in any laboratory criteria during examination of a person is always a reflection of the change in the state of functioning of the organism as a whole, which is observed both in diseases and may be physiological compensatory changes. When examining a blood test in relation to assessing the composition of blood cells, one should pay attention not so much to the change in their number, but to pathological changes in the shape, size and even color.

In a situation when the patient has anisocytosis in the blood test, there is a need to use additional methods of laboratory diagnostics, since the detection of these changes is a reflection of the presence of a serious disease.

Average sizes of blood cells are within 7 - 7.5 microns, and therefore the slightest deviation in the parameters is pathological anisocytosis (microcytosis, macrocytosis and megalocytosis).

Red blood units have different sizes, which is reflected in their names:

Normocytes are called cells whose size does not exceed 7.1 - 9 microns.

Microcytes up to 6.9 microns.

Macrocytes from 8 microns.

Megalocytes from 12 microns.

Important! In the blood of a healthy person, the content of normocytes should not exceed 70% of the total volume. As for microcytes and macrocytes, they account for up to 15%.

Thus, if in the analysis of blood it turns out that the level of large and small cells exceeds the maximum permissible values, this indicates an increase in the RDW value. Simply put, red blood cells will be of different size in blood smears.

When and how is their quantity checked?

Reasons to pass a blood test for reticulocytes are when:

  • suspected hemolysis,
  • Evaluation of erythropoiesis - the process of formation in the bone marrow of red blood cells,
  • monitoring therapy with folic acid, iron, vitamin B12, and erythropoietin,
  • monitoring bone marrow regeneration after transplantation

Prepare for the analysis you need correctly. To the results of the analysis were not distorted, should:

  1. blood donated on an empty stomach, only water is allowed,
  2. should take at least 8 hours after the last meal,
  3. it is necessary to donate blood before taking the medication or not earlier than two or three weeks after the abolition of such drugs. Otherwise, referral data for the study should indicate which drugs are taken, what their doses are,
  4. the day before blood donation, one should limit fatty, fried foods, exclude alcohol, and heavy physical exertion.

The results of the analysis may be affected by:

  1. insufficient mixing of anticoagulant and blood,
  2. wrong choice of anticoagulant,
  3. a blood transfusion that took place shortly before the test,
  4. hemolysis of blood samples
  5. taking corticotropin, sulfonamides, antimalarial drugs, levodopa, azathioprine, nonsteroidal analgesics, chloramphenicol, methotrexate, folic acid, vitamin B12, iron preparations, erythropoietin.

Little about transformation

Reticulocytes become erythrocytes due to the action of the hormone erythropoietin. They reveal granular, filamentous formations. This distinguishes reticulocytes from erythrocytes, where, under light microscopy, intracellular structures are not detected.

Reticulocytes are formed from normoblasts in the bone marrow, here they ripen in 1-2 days, and then reticulocytes replenish peripheral blood. Erythropoietin constantly excrete the kidneys in small quantities. When oxygen starvation begins, the hormone greatly saturates the blood.

If, due to any reasons, the destruction of erythrocytes begins (the hemoglobin of which is responsible for oxygenating the tissues), the process is accelerated, new reticulocytes begin to be intensively synthesized to compensate for the losses. To assess the activity of this process, reticulocytes are determined based on a blood test. That is, the activity of the process indicates the state of the bone marrow, kidneys, the possibility of the processes of destruction of red blood cells.

Norm of reticulocytes for men, women, children

The rate depends on sex only after 12 years, when menstruation begins in girls, and due to regular loss of menstrual blood (and with it, erythrocytes), an extended range of erythroid cell oscillations occurs.

The rate of reticulocytes is spelled out in modern analysis forms, where there is a separate field for this. These indicators and should focus. Reticulocytes are measured in ppm (denoted by the symbol ‰). If we talk about each age group specifically, the indicators of normal values ​​are (in):

Human ageNormal value
Children up to 2 weeks1,5–15
from 2 weeks to 1 month4,5–14
1-2 months4,5–21
2–6 months2,9–9
from 6 months to 2 years2–10
2–6 years old2–7
6-12 years old2–13
Women 12+
Men 12+



Common myeloid progenitor → Proerythroblast → Megaloblast → Polychromatic erythroblast → Normocyte → Reticulocyte Opportunities for further differentiationErythrocyte

Reticulocytes (from Lat. reticulum - reticulum and Greek. κύτοили - container, cell) - cells are the precursors of red blood cells in the process of blood formation, constituting about 1% of all red blood cells circulating in the blood. Also, like erythrocytes, they do not have a nucleus, but they contain residues of ribonucleic acids, mitochondria and other organelles, which, being deprived of which, are transformed into a mature erythrocyte.

Residual organelles are visible when stained according to Romanovsky and with the help of methylene blue. Compared with erythrocytes, reticulocytes have an even shorter lifespan. In the process of erythropoiesis (formation of red blood cells), they are formed and mature in the red bone marrow for 1-2 days, after which they leave it and for another 1-3 days they ripen in the bloodstream.


The functions of reticulocytes are generally similar to those of erythrocytes - they also capture and carry oxygen and carbon dioxide by blood, but their effectiveness is somewhat lower than that of mature erythrocytes.

Stages of development

With a lack of oxygen in the blood, the kidneys produce and release the hormone regulator erythropoietin, which is delivered to the red bone marrow and there causes the active process of formation of reticulocytes, which subsequently turn into red blood cells. During the development of the erythrocyte from the ancestor, the nucleus gradually disappears and hemoglobin protein appears.

Clinical and diagnostic value

To measure the number of reticulocytes, special automatic counters use a combination of laser excitation, detectors and fluorescent staining, which colors DNA and RNA in the cell. Among the cells in the blood stream, reticulocytes can be distinguished by the radiating signal. This signal is not as weak as in erythrocytes, but at the same time not as strong as in lymphocytes. When stained by Romanovsky reticulocytes are a slightly more bluish color. In addition, reticulocytes are on average more erythrocytes in volume. In humans, the normal amount of reticulocytes in the blood depends on the clinical condition, but on average varies from 0.5% to 2% in adults and from 2% to 6% in children. A newborn produces a large amount of erythropoietin in the first few days, and therefore the proportion of reticulocytes in the blood can reach 10%. Over time, the number of reticulocytes normalizes. A high percentage of reticulocytes in adults may be a sign of anemia, although it also depends on the state of the hematopoietic bone marrow cells.

Calculating the production index is an important step in understanding whether the number of reticulocytes will meet the needs of the body. Quite often, this is an even more important question than whether the percentage corresponds to the limits of the norm. For example, if a person has anemia, but the proportion of reticulocytes is 1%, then the bone marrow probably will not be able to generate enough cells that can correct anemia. A large number and percentage of reticulocytes in the blood are often observed with an increase in the production of red blood cells to overcome the severe loss of mature red blood cells (for example, with hemolytic anemia or blood loss). A large number of reticulocytes (above normal) is called reticulocytosis. An abnormally low number of reticulocytes may be caused by chemotherapy, aplastic anemia, malignant (B12-deficient) anemia, malignant diseases of the bone marrow, reduced erythropoietin production, iron or folate deficiency, and other causes.


Reticulocytes are a valuable tool for biologists to study protein translation. They are unusual due to the fact that they contain everything for the translation of proteins, but do not have a nucleus. Since there are many components in the cell nucleus that impede the study of translation, reticulocytes are very useful. Scientists can collect red blood cells from mammals such as rabbits, extract mRNA and translate enzymes to study the translation itself in vitro. This allows you to better control the conditions in which proteins are synthesized.

Indications for the study

Reticulocytes in the blood count are calculated when:

  • diagnosis of disorders of hemopoiesis,
  • suspected hemolysis,
  • malaria,
  • bites of poisonous spiders and snakes,
  • suspected hidden (internal) bleeding,
  • oncologic neoplasms,
  • monitoring erythropoietin production in patients after kidney transplantation,
  • identifying reduced or increased red blood cell count,
  • monitoring the regenerative capacity of the bone marrow after transplantation,
  • evaluating the patient's response to therapy (treatment with preparations of ferum, erythropoietin, folic acid, vitamin B12),
  • diagnosis of the quality of treatment with erythro-suppressor drugs.

The blood becomes more liquid by reducing the number of cellular elements with respect to the increased volume of plasma. A moderate increase in the number of reticulocytes is the response of a woman's body to the development of anemia.

Conducting and decoding the analysis

It is important to remember that the first count of the number of reticulocytes should be carried out before the start of taking drugs that stimulate their formation.

Blood sampling to count the number of reticulocytes should be carried out in the morning, on an empty stomach. Allowed to use water.

A day before the study, it was recommended to limit physical exertion and eliminate emotional overstrain. It is desirable to exclude alcohol intake in a week (if the analysis is carried out according to plan).

When interpreting the results, it is necessary to remember that some medications can change the reticulocyte index.

Reticulocytes will be reduced in patients taking:

  • cytostatics,
  • some antibiotics (sulfonamides, chloramphenicol),
  • antiepileptic drugs (carbamazepine),
  • anti-parkinsonian drugs
  • immunosuppressants.

Why reticulocytes may increase in the blood

  • hemolytic anemia (there may be an increase in the number of reticulocytes, up to 3000/00,
  • acute blood loss
  • toxic hemolysis (bites of venomous snakes or spiders, taking medication, toxic to red blood cells),
  • blood diseases ( polycythemia , thalassemia),
  • malaria,
  • pregnancy (moderately compensatory increase),
  • moving to highland areas (natural adaptation),
  • metastasis of distant malignant neoplasms in the bone marrow,
  • severe hypoxia (oxygen starvation of organs and tissues),
  • treatment of various anemias with ferum, B12 and folic acid preparations,
  • administration of erythropoietin.

Also, it should be noted that reticulocytosis can be:

  1. true (the main marker of KM regenerative capacity. It is characterized by an increase in the number of reticulocyte cells both in the bone marrow and in the general circulation,
  2. false (accompanied by the release of reticulocytes in the peripheral blood and the further depletion of their reserves in the bone marrow). This picture is typical for lesions of the bone marrow.

Reduced reticulocytes. The reasons

The decrease in the number of reticulocytes occurs when:

  • aplastic and hypoplastic anemias,
  • depletion of the regenerative capacity of the bone marrow,
  • B12 deficiency anemia,
  • primary tumor of the bone marrow directly or with its secondary metastatic lesion,
  • autoimmune diseases involving lesion of the hematopoietic system,
  • myxedema
  • kidney disease (reduced production of erythropoietin),
  • taking drugs that suppress bone marrow hematopoiesis,
  • alcoholism.

For those who abuse spirits, a decrease in the number of reticulocytes occurs for several reasons. Firstly, the hematopoietic function of the bone marrow is inhibited. Secondly, the production of erythropoietin is suppressed by the kidneys. Thirdly, the toxic effects of the decay products of alcohol contribute to the destruction of reticulocytes circulating in the blood, enhancing reticulocytopenia.

Symptoms of reticulocytosis

Reticulocytosis itself is not a pathology.Moreover, in some cases, this laboratory indicator is considered by experts as a sign of good bone tissue regeneration (true reticulocytosis). However, the number of reticulocytes should increase, not only in the peripheral blood, but also in the bone marrow itself.

If reticulocytosis develops on the background of aplastic anemia, the patient will complain of the following symptoms:

Increased fatigue and fatigue.

Pale skin.

Frequent nasal and gingival bleeding.

Diseases such as stomatitis, pneumonia, infections of the skin and urinary tract.

Hemolytic crisis is a syndrome that is accompanied by intravascular or intraorganic destruction of red blood cells.

The following signs indicate hemolytic crisis:

Tachycardia, shortness of breath, dizziness, pallor of the skin, or its icteric color.

Consciousness and convulsions.

Enlarged spleen in size.

Symptoms of latent bleeding depend on its intensity. Common signs include dizziness, shortness of breath, thirst, pale skin, fainting, or faintness. The rate of increase of these symptoms will depend on the intensity of the bleeding.

Malaria, which is accompanied by reticulocytosis, can begin acutely, or manifest a slight increase in body temperature, headaches, malaise. For 3-5 days the patient’s illnesses begin to pursue the attacks, which are alternately replaced by chills, fever and sweating. These paroxysms are repeated up to 10-14 times, after which there is an improvement. However, the disease tends to recur.

Polycythemia with reticulocytosis develops long and gradually. Most often, it is diagnosed randomly when performing a blood test. The patient is periodically worried about heaviness in the head, dizziness, his vision may deteriorate, and sleep disorders appear. The most pathognomic sign of polycythemia is vascular plethora, when the skin acquires a cherry-red color, especially noticeable in the face, neck, hands and mucous membranes. At the same time, the patient's hard palate has a normal color, and the soft palate acquires a cyanotic shade.

Acute hypoxia with reticulocytosis develops quickly, in a few minutes. If oxygen deprivation is not stopped, irreversible consequences occur in the organs and tissues and a person can die. This condition is manifested by the failure of all organ systems. First of all, the central nervous system suffers, breathing and heartbeat slow down, blood pressure decreases. Organ failure goes into a coma and agony, after which a person dies.

Causes of reticulocytosis

Causes of reticulocytosis may be the following:

Reticulocytes can reach a level of 60% with hemolytic anemia. Hemolytic crises lead to significant jumps of reticulocytes in the blood.

At 3-5 days after acute blood loss, all patients develop a reticulocyte crisis.

Increased reticulocyte levels may indicate latent bleeding, for example, in patients with peptic ulcer, typhoid fever, and other diseases of the gastrointestinal tract.

Malaria and polycythemia will cause reticulocytosis.

If the patient was diagnosed with iron deficiency anemia, then after 3-5 days from the start of treatment the level of reticulocytes will increase in the blood. This indicates the effectiveness of the therapy. A similar situation is observed in the treatment of pernicious anemia.

The hypoxia of the body provokes an increase in the level of reticulocytes in the blood.

Penetration of metastasis of tumors in the bone marrow leads to reticulocytosis.

Against the background of the massive destruction of red blood cells, the level of reticulocytes can rise to 50%.

Taking certain medications may trigger the development of reticulocytosis. These remedies include: Corticotropin, antipyretic and antimalarial drugs, Furasolidone, Levodopa.

The true reticulocytosis is indicated by an increase in the number of reticulocytes in the peripheral blood and in the bone marrow.

False reticulocytosis is indicated by an increase in the level of reticulocytes in the peripheral blood, but with their normal level in the bone marrow.

The following reasons can provoke a false reticulocytosis:

The presence of blood Taurus Jolly or malaria plasmodium.

Hemoglobin deformed form.

Presence in the blood of giant platelets.

Diagnosis of reticulocytosis

There are certain indications for performing analysis of reticulocytes:

The need to evaluate erythropoiesis with hemolysis or bleeding.

Assessment of the bone marrow's ability to recover after the patient’s treatment with cytostatics or after the operation on transplantation of this organ.

Evaluation of erythropoietin production in patients undergoing kidney transplant surgery.

Passing doping control by people who are professionally involved in sports.

Diagnosis of anemia, regardless of its cause.

Search for the causes leading to a decrease in the level of red blood cells.

Search for the causes that lead to the failure of the blood formation of the bone marrow.

Search for the causes that lead to a violation of the regenerative ability of the blood-forming organs during the treatment of anemia. Evaluation of the effectiveness of the treatment of anemia.

Evaluation of the effectiveness of therapy with erythropoietin or erythrosuppressors.

Counting of reticulocytes can be carried out in several ways: using the method of luminescent microscopy, counting the number of reticulocytes in a blood smear with the introduction of special dyes into it, counting the number of reticulocytes using a hemolytic analyzer.

Treatment of reticulocytosis

In order for the level of reticulocytes in the blood and in the bone marrow to return to normal, it is necessary to eliminate the cause that provoked their increase.

With aplastic anemia of a person must be hospitalized. To prevent infectious complications, it should be in an isolated box. Most often, patients with aplastic anemia are prescribed immunosuppressive therapy. At the same time, the patient receives injections of immunoglobulin and cyclosporine A. If necessary, he is transferred a platelet or erythrocyte mass, plasmapheresis is performed. Possible removal of the spleen. Bone marrow transplantation significantly improves the prognosis for patient survival.

In a hemolytic crisis, help to the victim should be provided immediately. He is urgently hospitalized, replenishes the volume of blood lost and eliminates the harmful products of hemolysis in the blood. For this, albumin, glucose solution, vitamin B2, sodium chloride, Desferal are injected intravenously. With the help of Furosemide, diuresis is stimulated to prevent the development of renal failure. To enhance the diuretic effect prescribed Euphyllinum. Be sure to use glucocorticoids to suppress the body's immune response. If necessary, the patient is transfused. In order to prevent re-crisis, the removal of the spleen is recommended.

Hidden bleeding should be promptly detected and stopped.

Treatment of malaria requires infusion therapy, heavy drinking, bed rest. To eliminate the infection from the body using quinine.

To normalize the volume of circulating blood requires bleeding in volumes up to 500 ml 2-3 times a week. The removed blood volumes are replenished using saline or reopolyglukine. In severe cases of polycythemia, cytostatics are prescribed or therapy with radioactive phosphorus.

Acute hypoxia requires the elimination of the causative factor and the maintenance of body cells with oxygen. At the same time, oxygen is injected into the lungs under pressure (hyperbaric oxygenation).

Treatment of reticulocytosis is reduced to the elimination of the pathological cause, if any. Often, an increase in reticulocyte levels occurs during the treatment of iron deficiency anemia and is a favorable prognostic sign. In this case, no therapeutic measures are needed. After some time, the reticulocytosis will be docked on its own.

Education: Moscow Medical Institute. I. M. Sechenov, specialty - “Medicine” in 1991, in 1993 “Occupational diseases”, in 1996 “Therapy”.

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