The term polycythemia is used synonymously with that of erythrocytosis. It stands for the fact that the amount of red blood cells, the so-called erythrocytes , is increased and that there is increased blood formation. The phenomenon of polycythemia can be recognized by an increased hematocrit value.
Polycythemia – when the blood flows more viscously
The hematocrit describes the percentage of cells in the blood by volume. The largest number of these blood cells are the red blood cells, the erythrocytes . The discovery that the red blood cells occur in excess in the body may be preceded by various causes.
There is either a relative, a so-called pseudopolyglobule, or an absolute polyglobule. In the case of the absolute, a distinction must again be made between primary and secondary polyglobules.
What is relative polycythemia?
In the case of relative polycythemia, a pathological reduction in the erythrocytes only appears to be present. The appearance is due to a shifted cell-plasma ratio, as reflected in the hematocrit. In pseudopolycythemia, the altered ratio is due to a high fluid loss, as occurs after prolonged vomiting and severe diarrhea.
According to the erythrocyte counts, it is a polycythemia that disappears again after the administration of liquid. A dehydration of the patient with previous fluid withdrawal is the reason for the laboratory diagnostic picture.
What is primary polycythemia?
Primary polycythemia manifests itself like the disease that doctors call polycythemia vera. This leads to a malignant transformation and proliferation of the stem cells in the bone marrow, which are the precursors of the erythrocytes. The result is that the density of cells per liter of blood increases.
This leads to reddening of the skin and high hematocrit values, which are expressed in the hyperviscosity of the blood. The blood flows more viscously due to the high number of cells in relation to the liquid content. The consequences are ischemia, insufficient blood flow to the brain or the coronary arteries, peripheral circulatory disorders and dangerous thrombosis.
How does secondary polycythemia develop?
Secondary polycythemia arises due to other primary diseases and, as a manifestation, is a consequence of these diseases. In retrospect, secondary polycythemia is preceded by increased production of erythrocytes resulting from increased erythropoietin or cortisol levels.
Both hormones are responsible for controlling and regulating the formation of erythrocytes. An elevated erythropoietin level is itself a symptom of various conditions or diseases. The doctor distinguishes between:
- compensatory polycythemia, in which the increased erythropoietin level is a reaction to a lack of oxygen in the blood, the cause of which can be found either in an altitude above 4,000 meters or a heart or lung disease,
- nephrogenic polycythemia, which occurs when there is a mass in the kidney caused by multiple cysts or tumors or by circulatory disorders,
- paraneoplastic polycythemia associated with tumor disease in the kidney, lung, liver or ovary.
An elevated cortisol level is an expression of Cushing’s syndrome.
Symptoms of polycythemia
Polycythemia manifests itself in the following symptoms:
- red-blue face, also colored hands and feet,
- purple to bluish colored lips known as lip cyanosis,
- dizziness and ringing in the ears,
- shortness of breath, nosebleeds, headaches,
- vision problems, concentration problems and depression,
- Angina pectoris, the so-called heart narrowing.
Therapy for polycythemia
The forms of therapy differ depending on whether the polycythemia is relative or absolute. In most cases of pseudopolycythemia, intravenous administration of substances that compensate for the loss of body fluids, such as electrolyte solutions, is sufficient.
The doctor treats critical hematocrit values with the help of bloodletting and the addition of plasma expanders, which increase the density of the cell plasma per liter of blood. If primary polycythemia is present, the symptoms are treated because the disease itself cannot be cured. Secondary polycythemia, on the other hand, requires treatment of the causative disease.
The lack of oxygen in the blood can be treated, for example, by administering oxygen.
Normal values for the number of erythrocytes
Normal values are the absolute number of erythrocytes, the hemoglobin value and the hematocrit value. The hemoglobin is instructive as it is responsible for binding oxygen in the erythrocytes. The number of erythrocytes in a healthy adult male is 4.3 to 5.7 million per microliter of blood. In a female adult there are 3.9 to 5.3 million erythrocytes per microliter of blood. For hemoglobin, the red blood pigment, the normal value for a male adult is 13.5 to 17 grams per deciliter, for a female adult twelve to 16 grams per deciliter. The normal hematocrit, as the proportion of blood cells to total blood, is 40 to 52 percent for a healthy man and 37 to 48 percent for a woman.
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