Blood is one of the basic components of the human body. It performs vital functions, thanks to which it ensures the maintenance and unity of homeostasis in the body. Blood consists of a liquid component, called plasma, and a cell mass. The largest percentage of cellular elements in the blood falls on erythrocytes (red blood cells). They bind oxygen from the air and transport it to all the cells and tissues of the body, thus maintaining their normal life cycle.
Erythrocytes are small double-indented disks that do not have a nucleus and have a relatively plastic membrane. They originate from an original (stem) cell in the bone marrow, which after several differentiations turns into a mature erythrocyte. Usually, erythrocytes live for about 120 days, after which various morphological changes occur in them and they are destroyed by the cells of the reticulo-endothelial system. However, thanks to a finely maintained regulatory system in a healthy organism, the number of erythrocytes always remains constant, which ensures the oxygen needs of the cells.
Anemia is a condition in which the total number of erythrocytes in the blood is lower than normal, resulting in tissue and cellular oxygen deficiency, which determines the occurrence of a pathological process.
Anemia is more a symptom of a given disease than an independent disease. That is why often the mere diagnosis of the condition is not enough to cure the patient. In most cases, it concerns an underlying disease with different characteristics, and anemia is simply its symptom. Its occurrence is often the result of disease manifestations in various organs, for example, the gastrointestinal tract, kidneys, bone marrow, etc. or it is due to an irrational and unhealthy diet.
It is currently estimated that between 8-10% of the world’s population suffers from this type of disease. This makes anemia the most common disease in the field of hematology. In addition, women suffer twice as often as men. Anemia occurs both in young and in older patients with the difference that in the latter the occurrence is more often due to various chronic pathological processes in the body.
How are erythrocytes formed?
Hemopoiesis is one of the most important and finely regulated mechanisms in the human organism. This process of blood cell production takes place primarily in the bone marrow. Erythropoiesis is the specific process of erythrocyte formation. Among the stem cells in the bone marrow, the first step in this mechanism is the unipotent progenitor cell, which is extremely sensitive to the action of a hormone called erythropoietin. Under its influence, the cell matures and gradually turns into the second unit of the process – proerythroblast. After 3-5 days of differentiation, this proerythroblast matures and gradually passes through different stages, to finally become a reticulocyte.
Reticulocytes are the last step before the appearance of mature erythrocytes. In contrast, the former still has a nucleus and an insufficient amount of hemoglobin. Gradually, the nucleus disappears, and functionally capable erythrocytes appear in the peripheral blood, which performs their functions for nearly 120 days. After that, various degenerative changes occur in them and they undergo degradation by the cells of the reticulo-endothelial system. The waste products obtained from the breakdown later serve as bone marrow material for the production of new erythrocytes, i.e. leave nothing superfluous for the body.
The speed with which the bone marrow produces red blood cells, and the speed with which the spleen breaks them down, is different depending on the needs of the body. At maximum stimulation, for example during acute blood loss, the bone marrow can be stimulated up to 8 times.
What are the types of anemia?
There are various classifications of anemia types. Most often, however, two possible classifications are discussed in practice – depending on the mechanism of occurrence and depending on the morphological characteristics of the erythrocytes themselves.
According to the mechanism of occurrence of the anemic state, anemias are:
insufficient production of erythrocytes – this can be due to lack of iron, lack of vitamin B12 and folic acid, various kidney damage or chronic lead poisoning.
severe blood loss
increased destruction of erythrocytes (hemolysis) – this may be due to pathological changes in the erythrocytes themselves, or to various immune-mediated and infectious diseases
anemias as a result of over-deposition of erythrocytes – with increased function of the spleen
anemia in the course of various malignant diseases of the bone marrow
anemia in the course of chronic inflammatory and neoplastic diseases
Depending on the morphological picture, anemias are microcytic and hypochromic (that is, the erythrocytes microscopically appear smaller and less colored), normocytic and normochromic (erythrocytes are of normal size and normal type of coloring) and macrocytic and hyperchromic (erythrocytes are larger scale and more saturated coloring).
Depending on the course of the course, we distinguish between acute anemia (usually acute blood loss), whose symptoms develop over the course of several days or even hours and are associated with a serious risk to the patient’s life, and chronic anemia, in which the manifestation of symptoms occurs gradually, even imperceptible.
There is a certain group of anemic conditions that are inherited, such as thalassemia, hemoglobinopathies, and others. They also have a certain racial predisposition, which greatly facilitates their diagnosis.
What are the main causes of anemia?
Anemia as a pathological condition largely resembles fever, i.e. it is an important but non-specific symptom, therefore a thorough elucidation of the underlying disease process is necessary. And this often turns out to be quite a difficult task, considering the wide variety of reasons that can lead to the appearance of a reduced number of erythrocytes in the body.
In general, the causes of anemia are the following:
- hereditary factors – some anemias such as hemoglobinopathies, thalassemias, enzyme disorders in the erythrocyte membrane, Fanconi anemia, and others are inherited. They appear most often in early childhood, and if one thinks about these diseases, their diagnosis is not a problem
- inadequate and unhealthy nutrition – unfortunately, this factor continues to be one of the leading causes of anemia. This includes insufficient intake of iron, vitamin B12, and folic acid, general malnutrition, and starvation
- acute bleeding – most often with esophageal varices in the course of liver cirrhosis, ulcer perforation, and others
- immune-mediated diseases – most often it is the so-called vasculitis
- use of various drugs and chemicals
- chronic diseases – liver and kidney complications, neoplastic diseases
- chronic infections
As you can see, the variety is extremely large. It is for this reason that a good knowledge of the pathophysiological and pathomorphological features of erythropoiesis (the mechanism of the formation of erythrocytes), correct clinical behavior, not underestimating the condition and, above all, experience, is necessary to be able to specify each anemic condition.
What are the characteristic signs of anemia?
The symptoms of anemia depend to a great extent on the speed of its development – in acute anemia they are extremely obvious, while in chronic cases the symptoms are not so pronounced, as the body manages to adapt over time to the reduced amount of erythrocytes.
Anemia should most often be thought of in one of the following complaints:
- general weakness
- easy fatigue
- general pallor
- a feeling of coldness out of proportion to the outside temperature
- out of breath
- chest pains
- visual disturbance and tendency to collapse especially when straightening the body
- headache
- inability to concentrate
- vertigo
- drowsiness and incomplete sleep
These are the most typical and frequent manifestations of anemia regardless of its type. With a more detailed examination and questioning of the patient, in many cases, the doctor can get a more comprehensive idea of the exact characteristics of the anemic condition. For example, if the patient is not eating well, is starving, or for some organic reason has no appetite, iron deficiency anemia can be thought of. If the symptoms listed above are accompanied by paresthesias (a special type of tingling in the legs) and atrophic changes in the mucous membranes and especially the tongue, it is possibly the so-called anemia due to vitamin B12 deficiency.
The lack of folic acid in the body is often accompanied, in addition to anemia, by a dry throat, as well as by manifestations of steatorrhea (discharge of fatty feces). If there are other representatives with anemic syndrome in the family, it is most likely a hereditary type of anemia. Anemia with sub-febrile temperature often suggests the presence of a chronic disease such as vasculitis or chronic infection.
How is anemia diagnosed?
Diagnosing the anemic syndrome is a relatively easy task, since the very appearance and complaints of the patient point to this disease. On the other hand, however, the pathological condition underlying the anemic syndrome often turns out to be one of the most complex problems for clinicians. The reason for this lies in the wide variety of factors that lead to the occurrence of the condition.
When the patient enters the doctor’s office, the first thing that makes an impression is the paleness of the skin and the visible mucous membranes. The appearance itself often leads to the diagnosis at the very beginning. Later, the patient’s complaints can largely confirm the suspicion of possible anemia. The diagnosis of anemic syndrome is made with the help of laboratory tests. It is necessary to make a complete blood count, which gives an idea of the state of the erythrocyte row.
The following indicators are important for making the diagnosis:
- hemoglobin – this is the red pigment in the erythrocyte. It is he who binds the oxygen from the lung and delivers it to the tissues and cells. Normal hemoglobin values are 120-160 for women and 140-180 for men. I.e. values lower than those indicated mean that the person has anemia.
- hematocrit – represents the percentage ratio of erythrocytes to the total volume of blood. Its values are 0.40-0.54 for men and 0.34-0.46 for women.
- erythrocyte count – normal values are 4.6-6.2 for men and 4.2-5.4 for women.
- MCV – ratio of hematocrit to the total number of erythrocytes in the blood, i.e. it gives information about the size of the cell. Based on this indicator, anemias are divided into micro-, normal– and macrocytic.
- MCH – represents the ratio of hemoglobin to the total number of erythrocytes. He divides anemias into hypo, normo- and hyperchromic.
- MCHC – the ratio between hemoglobin and hematocrit. Gives information about the hemoglobin content of the erythrocyte.
