Overview
Blood dyscrasias refer to any blood-related diseases. These disorders affect blood components, lymph tissues, vasculature and bone marrow. Blood dyscrasias are studies under haematolgy. Haematology is the scientific study of blood, its components and functions in health and disease. An individual may be affected by more than one blood disorder. Therefore, it is important to have general knowledge of these disorders.
Generally, blood disorders include conditions such as;
- Aplastic anaemia
- Anaemia of chronic disorders(ACDs)
- Polycythemia vera
- Sickle cell anaemia
- Thrombotic thrombocytopenic purpura(TTP)
- Hemochromatosis
- Iron deficiency anaemia(IDA)
Components of blood
Blood is composed of the liquid and cellular constituents. Liquid part of blood is referred to as plasma while the cellular component consists of white blood cells, red blood cells and platelets.
Blood plasma is about 55% of the total blood volume. It contains substances such as hormones, clotting factors like fibrinogen, other proteins suuh as albumin, nutrients and electrolytes.
Causes of Blood Disorders
- Idiopathic. This is used to refer to unknown causes of the condition. It may be uncertain or completely not known.
- Genetic mutations. For example in sickle cell disease where Hb A becomes Hb S
- Cancers. Blood dyscrasias include some cancers such as leukaemias. Examples of leukaemias are AML, CML, ALL, CLL. Cells that are leukaemic can crowd in the bone marrow leading to decreased production of other types of cells of the blood.
- Environmental exposures. For example chemicals and radiations.
- Vitamin and mineral deficiencies
- Medications and drugs. Both medicines and drugs of abuse can cause blood dyscrasias.
- Infections
- Auto-immune diseases. Antibodies attack self-cells
Types
These disorders are classified according to the type of cell lineage that is affected.
Red blood cell disorders;
- Polycythaemia. This refers to an increase in red blood cells. It can be hereditary or caused by other factors such as high altitude. In polycythaemia, the body badjusts to lack of oxygen by increasing number of red cells.
- Enzymopathies. These are red blood cell enzyme defects. Examples are glucose-6-phosphate dehydrogenase deficiency and pyruvate kinase deficiency.
- Haemolytic anaemias. These are caused by haemolysis or break down of red cells.
- Nutritional deficiencies. Examples are Iron deficiency anaemia and megaloblastic anaemia due to Vitamin B12 deficiency.
- Red cell defects. Examples are ellliptocytosis and hereditary spherocytosis.
- Haemoglobinopathies. Haemoglobinopathies can be hereditary or acquired. Examples of hereditary haemoglobinopathies include sickle cell disease(SCD) and thalassaemia while acquired haemoglobinopathies include sideroblastic anaemia.
White blood cell disorders;
- Leukopenia refers to decreased white blood cells due to chemotherapy and infections.
- Leukaemias. For example AML, ALL, CML and CLL. These are ; Acute Myeloid Leukemia (AML), Acute Lymphocytic Leukemia (ALL), Chronic Myeloid Leukemia (CML) and Chronic Lymphocytic Leukemia (CLL).
- Leukocytosis. Elevated white cell numbers due to infections. Eosinophilia(elevated eosinophil count) symbolizes presence of parasitic infection.
Platelet disorders;
- Increased platelet numbers(thrombocytosis) in inflammatory conditions.
- Decreased platelet counts(thrombocytopenia) due to blood loss and marrow disorders.
Diagnosis & Tests
For proper diagnosis, first of all conduct a medical history in order to obtain patient history. Patient history-taking is very relevant.
White blood cell tests.
For example; white cell count. The test is done to check for number of white cells in a blood sample.
Leukocytosis(a high white blood cell count) symbolizes presence of infections.
Red blood cell tests.
These include;
- Haemoglobin test- to check for haemoglobin levels in blood samples
- Reticulocyte count. Reticulocytes are erythrocytes that are not yet fully matured. The test is conducted to check whether the bone marrow is producing adequate healthy erythrocytes.
- Haematocrit test. It is used to quantify the percentage of red blood cells present in blood.
Platelet tests
Platelets are responsible for clotting of blood and stopping excessive loss of blood after vascular injury.
Platelet tests are listed below;
- Peripheral blood smear. This test checks platelet morphology under a microscope.
- Mean platelet volume test. To check for sizes of platelets.
- Platelet count. This test is used to quantify platelet numbers in blood.
Conclusion
It is good to have general knowledge of these disorders.
In another article, we shall discuss specific symptoms, treatment and management, and prevention of some of these blood disorders.