Human blood carries oxygen from the lungs to all tissues of the body. Red blood cells – erythrocytes – are necessary for this. But sometimes there are not enough red blood cells in the body to carry oxygen in sufficient quantities: You have anemia (anemia). But how does this happen and what does it mean for the person affected?
How is blood made in the body?
Red blood cells, or erythrocytes, are responsible for transporting oxygen throughout our bodies. They contain a certain amount of hemoglobin. This protein, via an iron ion, can bind and also release oxygen. In order for oxygen transport to function, the erythrocytes, including hemoglobin and iron ion, must be intact. The red blood cells are formed by the bone marrow. Blood formation is also called hematopoiesis in medical terms. It is stimulated by the hormone erythropoietin, which is mainly produced in the kidney. When less oxygen than normal and necessary is available to the tissue, erythropoietin is released. It then stimulates blood formation in the bone marrow. For this to occur smoothly, various substances – especially iron, vitamin B12 and folic acid – must be available in sufficient quantities.
How does anemia develop?
When a problem occurs in any step of blood formation or its regulation, anemia occurs. The medical term for anemia is anemia. It occurs when there is too little hemoglobin and/or too few erythrocytes in the blood. Few erythrocytes can be recognized in the blood count by a low hematocrit. The hematocrit indicates how large the proportion of the various blood cells is in the blood. The blood cells include the red blood cells (erythrocytes), the platelets and the white blood cells (leukocytes). However, the number of platelets and leukocytes does not have a great influence on the hematocrit, because they are proportionally much less in the blood than the erythrocytes. For this reason, the hematocrit is used to assess the erythrocyte value. Anemia can have various causes, such as iron deficiency, vitamin B12 deficiency or internal bleeding. A blood count can already give the doctor an indication of the possible underlying problem.
Where can anemia come from?
There are many causes of anemia; however, there are three main mechanisms that lead to anemia.
- Bleeding (acute or chronic)
- An increased breakdown of red blood cells (enzyme errors, medications).
- A decreased formation of hemoglobin or red blood cells (iron deficiency, chronic diseases).
Depending on what is the cause of anemia, different changes in the blood show. At these, the doctor can not only recognize the cause. A classification of the different types of anemia is also possible through these changes.
How do you notice anemia?
The signs of anemia are caused by the low presence of oxygen in the tissues, which is due to decreased oxygen transport. The body tries to compensate for the low hemoglobin level and still get enough oxygen to all the tissues of the body via a faster heart and breathing rate. However, this is only possible up to a certain point. Those affected notice the following symptoms in themselves accordingly:
- Low physical resilience
- Palpitations and shortness of breath (especially under stress)
- Fatigue
- Weakness
- Paleness, which is particularly well seen on the mucous membranes (for example, the inner sides of the eyelids).
Most often, anemias are chronic, that is, they develop over a long period of time. This allows the body to start compensatory mechanisms and the affected initially do not notice the anemia. Young people in particular can still live unrestrictedly even with quite pronounced anemias.
Which blood values are important in anemia?
The diagnosis of anemia is made by blood values. Most often, anemia is discovered by chance when a blood count is done for some other reason. In this blood count, it is then noticed that the hemoglobin (Hb) level is too low. According to the WHO definition, the lower limit is 120 g/l of blood in women and 130 g/l in men.In the next step, the doctor then looks at the mean corpuscular volume (MCV) and the mean corpuscular hemoglobin (MCH) in the blood count. These two values show how large a single red blood cell is and how much hemoglobin it contains. Depending on how these values turn out, the doctor can draw initial conclusions about the underlying problem. The normal values of the blood parameters differ from person to person. For example, they are influenced by:
- Age
- Gender
- Pregnancy
- Smoking
- Stays at high altitude
Blood tests also look for iron levels (ferritin, transferin, serum iron), signs of increased erythrocyte breakdown (hemolysis signs) and altered hematopoiesis, as well as folic acid and vitamin B12, which can also be indicative of a diagnosis.
What tests confirm the diagnosis?
After an abnormal blood test, another interview to clarify the medical history and a physical examination will further help the health care provider determine the causes of anemia. The following physical examinations may be performed:
- Assessment of the skin and mucous membranes
- Listening to the heart
- Blood pressure measurement
- Examination of the abdomen
- Digital rectal examination
- For women, a gynecological examination
- Cancer screenings
Exactly which tests are performed depends on the medical history and the suspected cause of anemia.
Anemia: what types are there?
There are very many different types of anemia, which vary in their causes and effects. Based on mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH), classification into three classes is possible:
- Microcytic hypochromic anemias.
- Normocytic, normochromic anemias
- Macrocytic, hyperchromic anemias
Microcytic, hypochromic anemias
In these anemias, the erythrocytes are too small and contain too little hemoglobin. Microcytic hypochromic anemias include:
Iron-deficiency anemia
Iron deficiency is the most common cause of anemia. Iron is the central component of hemoglobin that enables oxygen transport. If there is too little iron in the body, correspondingly less hemoglobin can be formed and oxygen can be transported. Iron deficiency anemia is significantly more common in women (five times more common) than in men. The cause of iron deficiency is usually heavy menstruation or malnutrition. For therapy, those affected are given iron supplements to enable the body to once again produce sufficient blood.
Anemia of chronic disease
Chronic diseases cause anemia second most often. Anemia occurs because the underlying disease interferes with iron metabolism and red cell production. Diseases that can lead to anemia include tumors (cancer), inflammation, and autoimmune diseases such as Crohn’s disease.
Thalassemias
Thalassemia is an inherited form of anemia that occurs particularly in the Mediterranean region. Affected individuals cannot produce normal hemoglobin due to a genetic defect.
Normocytic, normochromic anemias.
Here, the erythrocytes are normal in size and also contain the normal amount of hemoglobin. Only their number is reduced, resulting in anemia. Below, we present the different forms of normocytic normochromic anemia.
Normocytic, normochromic anemia due to acute bleeding.
Anemia due to acute bleeding can quickly become life-threatening. It is important to stop the bleeding as soon as possible and stabilize the affected person’s circulation.
Hemolytic anemias
In this form, the red blood cells are destroyed or broken down too early (normal life span: 120 days). The reason for hemolysis may be internal to the cells (altered hemoglobin, broken membranes) or external (vascular damage, heart valve defects, infections). There is also autoimmune hemolytic anemia, in which the body’s own antibodies bind to the erythrocytes, causing them to break down. Another special form of hemolytic anemia is sideroblastic anemia.It is inherited via the X chromosome and therefore mainly affects men, since in women a healthy X chromosome can compensate for a diseased one and thus prevent the onset of the disease. The so-called spherocytic cell anemia or spherocytosis also belongs to the hemolytic anemias. It is caused by a genetic defect that damages the structure of red blood cells.
Renal anemias
When the kidney stops working properly, medical professionals refer to it as renal failure. In the course of chronic renal insufficiency, so-called renal (ren = kidney) anemia also occurs because the kidneys do not secrete erythropoietin or secrete less erythropoietin, and thus blood formation is no longer sufficiently stimulated. In addition, renal insufficiency causes red blood cells to be broken down more rapidly.
Aplastic anemia
In aplastic anemias, there is a disorder in the bone marrow. The blood-forming cells of the bone marrow are probably destroyed by an immune response. Thus, not enough blood can be regenerated. Often, not only are there fewer erythrocytes, but the number of other blood cells is also reduced. There are both congenital and acquired forms of aplastic anemia. The congenital forms include Fanconi anemia, which is associated with malformations and an increased risk of cancer. A special form of aplastic anemia is Pure Red Cell Anemia. It affects only the red blood cells. The other cells are not affected in their numbers. The congenital form of this disease is called Diamond-Blackfan anemia.
Macrocytic hyperchromic anemias.
In macrocytic hyperchromic anemias, the number of red blood cells is reduced. To compensate, each red blood cell is loaded with more hemoglobin. As a result, the erythrocytes are larger than normal. However, compensation for the low red cell count is not completely possible, which is why anemia occurs.
Megaloblastic anemia
A vitamin B12 or folic acid deficiency leads to a disruption in DNA production. As a result, red blood cells can only be produced in smaller quantities. However, these are compensatingly loaded with more hemoglobin, making them larger than normal. A risk factor for vitamin B12 deficiency is a vegetarian or vegan diet, although sufficient intake of the vitamin is possible without animal products through a conscious diet or by taking vitamin supplements. Sufficient vitamin B12 is stored in the body for several years, which is why anemia often appears late. A special form is pernicious anemia. Vitamin B12 is absorbed in the stomach via a glycoprotein called intrinsic factor. There is an autoimmune disease in which the intrinsic factor is prevented from binding vitamin B12 by the body’s own antibodies. As a result, the vitamin can no longer be absorbed and anemia results.
Myelodysplastic syndrome
Myelodysplastic syndrome often affects people of older age. In the bone marrow, some defective cells begin to multiply rapidly. This displaces the normal hematopoietic cells and normal hematopoiesis can no longer occur. This syndrome can progress to acute myeloid leukemia despite appropriate therapy, which significantly worsens the prognosis.
Anemia in the elderly
Many elderly people suffer from anemia. Until a few years ago, this was considered normal. However, just as in younger people, anemia in the elderly can be a sign of disease, internal bleeding, or cancer. Even if this is not the case, the symptoms of anemia limit the daily life of those affected and can promote mental and physical problems. That is why low hemoglobin levels in the elderly are now followed by evaluation and, if necessary, treatment for anemia.
Anemia in pregnancy
During pregnancy, drastic adaptations of the female body to new circumstances take place. During this time, lower hematocrit and hemoglobin levels are considered normal. In addition, the expectant mother needs significantly more iron, vitamin B12 and folic acid. Insufficient intake of these substances makes anemia during pregnancy possible, which is why most women are provided with appropriate supplements as a precaution. Anemia during pregnancy carries risks for complications such as premature birth and placental insufficiency (functional weakness of the placenta).
Anemia and sport
Male and female endurance athletes often have low hematocrit and hemoglobin. However, this is not true anemia. Exercise increases blood volume, but the blood plasma fraction (the liquid part of the blood without cells) increases more than the cell fraction. Thus, a dilution of the blood takes place and the hematocrit decreases. Nevertheless, athletes should ensure a good iron intake because they lose more iron through sweat and urine. Iron loss via urine during sports can have various triggers. These include, for example, minor injuries to the bladder caused by shock or drinking too little. This causes very slight bleeding within the bladder, which in turn results in iron loss. When there is anemia, the body is less able to withstand stress. Even normal everyday exertion, such as riding a bicycle to work and walking to the bus stop, puts the body through a task that otherwise only pronounced sports training can do. It is therefore important not to overload oneself and to listen to one’s own body when the limit of endurance has been reached.
What to do about anemia?
The treatment of anemia depends on its cause. Unfortunately, there is no cure-all for anemia. It is important to identify and treat the cause of the anemia. For example, iron supplements are given to those with iron-deficiency anemias, bleeding is stopped, and attempts are made to stop chronic disease. In very severe anemias, hospitalization may be necessary to stabilize the circulation and monitor the affected person. Blood may then also have to be transfused. The decision to do so is influenced by a variety of factors such as the duration of the anemia, the age and previous illnesses, and the symptoms of the affected individuals.
What to look for in anemia
It is important to follow the therapy prescribed by your doctor or health care professional and not to overload your body. It is also a good idea to eat a balanced diet with adequate iron intake and healthy foods. Foods containing iron include meat products and offal but also green vegetables, legumes and whole grain cereals. Vegans or vegetarians should best consume iron-containing foods in combination with vitamin C (such as a glass of orange juice), as this improves the body’s absorption of plant iron.
How dangerous is anemia?
Anemia is a serious symptom. It indicates an underlying disease and, accordingly, is not a disease in its own right. These underlying diseases can usually be relatively harmless and well treated, such as iron deficiency. However, they can also be complex and even life-threatening, such as cancer or untreated thalassemia. The hemoglobin level at which anemia becomes critical, i.e., at which organ functions are restricted by the inadequate oxygen supply, depends on the patient and his or her physical condition. The critical value in young healthy people is lower than that of older people with heart disease, for example. In extreme cases, anemia can be fatal if left untreated. However, treatment is usually well possible, so that life expectancy is not limited by most anemias. An exception is some congenital anemias, which can only be treated purely symptomatically and cannot be cured.
