Hematology is the study of blood and its functions. This branch of medicine refers to the physiology and pathology of the blood. Hematology is of great importance in routine diagnostics, in the follow-up of a wide variety of diseases, but also in basic research. More than 90 percent of all medical diagnoses are based on hematological findings.
What is hematology?
Hematology is the study of blood and its functions. This branch of medicine refers to the physiology and pathology of the blood. Hematology is a combined word of Greek origin from the two syllables haima, the blood, and logos, the teaching. Consequently, hematology literally means the study of blood. In clinical application, the focus is particularly on the pathology of the blood. The blood composition is altered in a characteristic way in a wide variety of diseases, so that hematological values allow direct conclusions to be drawn about defective bodily functions. Basically, the science of hematology consists of so-called numerical hematology and cellular hematology. Numerical hematology is primarily concerned with normal values and circulating blood cells that deviate from these normal values. Cell hematology as a subfield includes the analysis of cell structures of blood cells or cells of the bone marrow. The most important cell hematological method is the so-called differential blood count of the white blood cells, leukocytes. Another subfield of hematology is hematooncology, which deals specifically with malignant neoplasms of the blood or bone marrow. The best-known hematological malignant disease is leukemia, and about 500 different forms of leukemia are known to date. While some of them have an exceedingly good prognosis and chance of cure for the patient, other forms, for example acute lymphoblastic leukemia, lead to death within usually a few weeks after diagnosis.
Treatments and therapies
The simplest specialized hematologic examination is to obtain a small blood count, consisting of leukocyte, erythrocyte, platelet, and hemoglobin counts. It is a general examination in the family doctor’s office or as an initial examination in case of hospitalization. Normal values can already rule out many diseases. However, if the values of the blood count are significantly altered, these pathological findings must always be further clarified for differential diagnosis. The most important normal hematological values are leukocytes 4000-9000, erythrocytes 4.5-5.5 million, platelets 180,000-300,000, hematocrit 38-41% and hemoglobin 12-17g. All data are based on 1 cubic millimeter of whole blood. Hemoglobin is the blood pigment contained in the red blood cells, erythrocytes. Hemoglobin has the ability during gas exchange in the lungs to bind oxygen to itself and thus supply all body cells with vital oxygen through the bloodstream. If there is a deficiency of hemoglobin due to an illness or an accident, the hemoglobin level can be raised again by administering blood preserves, so-called erythrocyte concentrates. However, this is usually unsuccessful if the cause of the drop in hemoglobin is internal bleeding, for example in the gastrointestinal tract. The hematocrit value reflects the volume fraction of all cellular components in the total blood. With the exception of the differential blood count, all numerical hematological parameters are now determined with fully automated equipment in medical laboratories. However, differential blood counts require manual microscopic examination of the stained blood smear. The main focus is on the breakdown of the white blood cells into the individual leukocyte fractions. Important leukocyte fractions are neutrophil granulocytes, basophil granulocytes, eosinophil granulocytes and small and large lymphocytes. They all occur physiologically in the flowing blood. Bone marrow cells, such as plasma cells, myelocytes, metamyelocytes or promyelocytes, do not normally occur in the blood. If these are seen in the differential blood picture, one also speaks of a left shift, which is always to be regarded as pathological. The most common causes of a left shift are inflammatory changes and infections. This type of left shift is reactive, i.e. reversible, and disappears with therapy.In contrast, in leukemia, the leftward shift is irreversible, so the pathologic bone marrow cells appear permanently in the bloodstream.
Diagnosis and examination methods
All hematologic examination methods are part of laboratory medicine. The blood is examined hematologically in the medical laboratory by specially trained personnel, the medical technical laboratory assistants, MTLA. For this purpose, the venously drawn blood must be rendered unclottable. An anticoagulant, EDTA, is therefore included in the blood tubes for hematological testing. The technical and medical validation and release of hematological findings is always the responsibility of a specialist in laboratory medicine. Special semi-automated or fully automated machines are used for cell hematology, which can analyze a large number of blood samples hematologically within a very short time under the supervision of laboratory personnel. Hematological diagnosis appears simple at first, but then becomes quite complex when it comes to assigning pathological findings to a patient’s symptoms. In the case of a large number of hematological diseases, interdisciplinary cooperation between laboratory medicine, pathology, cytology and also radiology is therefore required. In the therapy of hemato-oncological diseases, hematology values are used primarily for monitoring the course of the disease, because the parameters allow significant conclusions to be drawn about the course and prognosis of hematological diseases. Hematological diseases are very multilayered and complex. The most important hematological diseases include leukemias, lymphomas, the various types of anemias, hemoglobin formation disorders and the so-called storage diseases such as hemochromatosis. The prognosis of hematological diseases is particularly dependent on genetic factors. To date, it has not been possible to influence these genetic factors in detail. Hematology has made considerable progress in recent years, but the research spectrum is far from being exhausted. Therefore, the changes in this subfield of laboratory medicine have the potential to fundamentally change medicine on patients in the future through basic research.
