Hemolysis is the breakdown of red blood cells under the influence of various factors, releasing hemoglobin into the blood plasma. Haemolysis can occur for a variety of reasons, and when it is severe, it leads to haemolytic anemia. What are the causes of hemolysis? How is it manifested? How can we diagnose and treat it?

Hemolysiscan occur as a result of congenital or acquired disorders. Congenital causes are mainly defects in the structure of erythrocytes, which lead to their premature breakdown. Such defects include, for example, congenital spherocytosis or ovalocytosis, which are defects in the erythrocyte cell membrane, enzymopathies such as glucose-6-phosphate dehydrogenase or pyruvate kinase deficiency, as well as defects in the structure or number of hemoglobin chains, i.e. hemoglobinopathies and thalassemia, respectively.

In addition to the causes of hemolysis, which are congenital causes, hemolysis can also be caused by nocturnal paroxysmal hemoglobinuria, which is another intracellular factor that induces hemolysis.

Haemolysis occurs more often due to extracellular factors, i.e. factors that are not related to the structure or function of erythrocytes. These include immunological factors - autoimmune or the body's reactions after transfusion of blood that is incompatible with the recipient's blood. In addition, for example, chemicals, bacterial or parasitic infections, or strenuous exercise can contribute to hemolysis.

A very common cause of haemolysis is hypersplenism, i.e. increased destruction of red blood cells by the most frequently enlarged spleen. Therefore, haemolysis in this mechanism will be caused by diseases that cause enlargement of the spleen and thus intensification of its activity. Some drugs, such as ribavirin, can break down red blood cells. Haemolysis may also occur as a result of damage to red blood cells by mechanical factors, such as artificial heart valves.

Classification of hemolysis

Hemolysis can be intra- or extra-vascular. Then the blood cells are broken down, respectively, in the lumen of the vessel or outside it, in the reticuloendothelial system.

Intravascular haemolysis may occur as a result of: a post-transfusion reaction, massive burns, the aforementioned nocturnalparoxysmal hemoglobinuria, physical trauma, various infections and as a result of microangiopathy.

Extravascular hemolysis can occur through immune mechanisms, hemoglobinopathy, red blood cell defects (for example, congenital spherocytosis), hypersplenism, or in a variety of liver diseases.

Hemolysis - how can it manifest itself?

Haemolysis may manifest as hyperbilurubinemia as bilirubin is released from the decaying red blood cells, which in high concentrations in the blood will result in jaundice.

As a result of the breakdown of erythrocytes, the amount in the bloodstream decreases, which signals to the bone marrow that it is necessary to increase the production of red blood cells. Therefore, in laboratory tests, we will see an increase in the percentage of reticulocytes, that is, immature forms of erythrocytes that try to "fill in the gaps" in the periphery. In addition, it is possible to detect hemoglobinuria and hemosiderinuria as well as a decrease in the concentration of free haptoglobin.

If the haemolysis is so severe that it leads to haemolytic anemia, the patient may present the symptoms typical of anemia, such as pale skin, weakness, decreased exercise tolerance, and tachycardia. In addition, the aforementioned jaundice and splenomegaly will appear.

Sometimes acute anemia appears in the form of a hemolytic crisis, which can even lead to acute renal failure. It should also be mentioned that haemolysis due to congenital causes manifests itself already in the youngest patients, others may appear only at a later age. The duration and severity of hemolysis are also important.

Long-term, low-intensity hemolysis will allow the body to gradually adapt to adverse conditions, therefore the symptoms will not appear immediately. It is different in the case of sudden or very severe haemolysis, which will cause acute symptoms.

In addition, specific causes of hemolysis may have symptoms that are typical for them, which I will try to briefly describe below:

  • congenital spherocytosis - may be accompanied by hereditary bone development disorders and gall bladder stones
  • glucose-6-phosphate dehydrogenase deficiency - acute attacks of hemolysis, typically occurring in men, caused by various factors, for example drugs (chloroquine, doxorubicin, high doses of vitamin C), certain foods, infections or stress
  • thalassemia - hemolysis typically occurs in the first year of life and is often accompanied by splenomegaly
  • sickle cell anemia - severe symptoms such as jaundice, jaundice stones,growth and development retardation, enlargement of the heart, peripheral congestion, ulceration around the ankles, but the earliest and most common occurrence are severe recurrent pains in the hands and feet
  • paroxysmal cold hemoglobinuria - symptoms typically appear minutes or hours after exposure to cold, and include back, leg and abdominal pain, chills and fever, as well as red or reddish brown urine

Hemolysis - how to diagnose it?

In hemolysis, typical, previously mentioned clinical symptoms may sometimes appear, which may lead the doctor to an appropriate diagnosis. In addition, laboratory tests are helpful, in which, in addition to anemia, hyperbilirubinemia and possible increase in lactic acid concentration, deviations typical for specific diseases can be shown, which seem to be too detailed to be discussed here.

In addition, a general urine test during intravascular haemolysis may reveal hemoglobinuria and dark colored urine. Bone marrow examination and ultrasound of the abdominal cavity are also helpful.

Hemolysis - treatment methods

General recommendations for the treatment of haemolysis, regardless of its cause, are based on the treatment of the underlying disease in secondary haemolysis, and in chronic primary haemolysis, folic acid and, very rarely, iron can be used as an adjunct. Red blood cell concentrate is only infused if there is severe anemia.

There are also specific treatments for each cause of hemolysis. In paroxysmal cold hemoglobinuria, it is usually enough to avoid exposure to cold, sometimes glucocorticosteroids can be used as an adjunct. Thalassemias are treated with vitamin C and zinc, and autoimmune causes are usually tried to be treated with immunosuppressive treatments.

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