What Is Blood?
Blood is the primary connective tissue in the form of fluid and circulates in the blood vessels carrying vital elements to the body. Blood is composed of different cells circulating in a protein fluid called plasma. Plasma is a fluid mixture of water, protein, and insoluble substances.
The three main types of blood cells are,
Red blood cells or erythrocytes.
White blood cells or leukocytes.
Platelets or thrombocytes.
What Is Total Blood Volume?
The blood volume in humans is five to six liters.
White blood cells and platelets comprise about one percent of the blood volume.
Plasma is the most significant portion of the blood volume.
Hematocrit, the percentage of packed red blood cells in the blood, comprises 39 percent to 50 percent of the volume.
What Are Hematological Disorders?
Hematological disorders are defined as disorders related to the blood and its components.
The disorders can be malignant or non-malignant. For example, there can be disorders related to red blood cells, white blood cells, platelets, lymph, or spleen.
What Are Malignant Hematological Disorders?
Malignant hematological disorders are cancer-related disorders in the blood-forming cells and bone marrow. In malignancy, the normal production of blood cells is disturbed and prevents the blood from performing its functions.
What Are the Types of Malignant Hematological Disorders?
The type of malignant hematological disorders are following-
Leukemia is a white blood cell-related disorder characterized by malignant forming cells primarily in bone marrow, leading to excessive production of white blood cells (leukocytes), resulting in the circulation of abnormal or immature white blood cells in the bloodstream.
Leukemia can be classified based on cell types into two -
Myeloid Leukemia: Myeloid (myelogenous) leukemia is the type of leukemia that arises from myeloid progenitor cells responsible for producing erythrocytes, granulocytes, monocytes, and platelets.
Lymphoid Leukemia: Lymphoid (lymphoblastic, lymphocytic) leukemia arises from the lymphoid stem cells, which include B-cell, T-cell, and NK cells.
Leukemia can be classified based on natural history:
Acute Leukemia: Acute leukemia leads to the excessive production of malignant cells that crowd out normal blood cells.
Chronic Leukemia: Chronic leukemia leads to the accumulation of abnormal white blood cells that fail to die and accumulate in the bone marrow, blood, and other organs.
What Are the Causes of Leukemia?
Exposure to high-dose radiation.
Alkylating agents, benzene, and formaldehyde.
Viruses-like human T-cell leukemia virus (HTLV).
What Are the Clinical Features of Leukemia?
Acute leukemia occurs commonly in children and young adults, and chronic leukemia occurs in mid-age adults and older people.
Males get more affected than females.
Swollen lymph nodes.
What Are the Types of Leukemia?
a. Acute Lymphocytic Leukemia: Acute lymphocytic leukemia refers to the abnormal growth of the lymphocytes. Bone marrow produces immature lymphocytes in excessive amounts. The immature lymphocytes crowd the normal cells and cannot perform their functions. Most commonly seen in children and spreads to lymph nodes, the liver, and other organs.
b. Acute Myeloid Leukemia: Acute myeloid leukemia refers to the excessive production of immature leukocytes called myeloblasts that rapidly fill the bone marrow and crowd the normal cells leading to sudden progressing infections. Most commonly seen in adults and involves lymphadenopathy, bone pain, and enlargement of the liver and spleen.
c. Chronic Myelogenous Leukemia: Chronic myelogenous leukemia is a very uncommon kind of leukemia; it is a myeloproliferative disorder characterized by the excessive proliferation of myeloid cells in the bone marrow. Commonly patients have a chromosomal abnormality known as the Philadelphia chromosome. Primarily seen in adults and old age groups of people.
d. Chronic Lymphocytic Leukemia: Chronic lymphocytic leukemia is the accumulation of mature lymphocytes in the bone marrow. It is the most typical type of leukemia, affecting old age; males are more affected than females.
e. Hairy Cell Leukemia: Hairy cell leukemia is a lymphoid neoplasm of B cell type of lymphocytes, also called leukemic reticuloendotheliosis. It is characterized by splenomegaly, abnormal mononuclear cells with hairy cytopenia, and projections on the surface. These hairy cells are seen in the peripheral blood and bone marrow.
2. Myelodysplastic Syndrome (MDS):
Myelodysplastic syndrome comprises a group of disorders which represent steps in the progression and development of leukemia. It is a heterogeneous group of clonal stem cell disorders characterized by the following:
a. Cytopenias due to impaired blood cell production.
b. Hypercellular and dysplastic bone marrow.
c. Genetic abnormalities.
d. Ineffective hematopoiesis.
3. Hodgkin’s Lymphomas:
Hodgkin’s lymphoma is a lymphoid neoplasm that arises within the lymph nodes. The significant cells present in Hodgkin's lymphomas are called Reed-Sternberg cells. It is commonly present in adults and has a bimodal age distribution in both genders.
- Painless swelling of lymph nodes in the cervical region.
4. Non-Hodgkin’s Lymphomas:
Non-Hodgkin's lymphomas comprise a large group of heterogeneous neoplasms of lymphoid tissues and blood. This malignancy does not contain Reed-Sternberg cells. It arises from T cells, B cells, and natural killer cells. The lymph nodes of the neck and the head are commonly involved as the extranodal tissues of this area.
- It is more common than Hodgkin's lymphoma.
- Seen in children and young adults.
- Non-Hodgkin's lymphoma is more common in males than in females.
- Painless lymphadenopathy is seen.
- Extranodal involvement of the gastrointestinal tract leads to bowel obstruction, and bone marrow involvement leads to recurrent infections and fatigue.
What Are Non-Malignant Hematological Disorders?
Non-malignant hematological disorders are non-cancerous disorders related to blood and its components.
What Are the Types of Non-Malignant Disorders?
The following are the non-malignant blood disorders -
Anemia is a blood-related disorder characterized by the reduction in:
Red blood cell count.
Packed cell volume.
This reduction occurs because of the following:
All these incidents are caused by inherited disorders, environmental factors, malnutrition, infections, and exposure to drugs or toxins.
What Are the Signs And Symptoms of Anemia?
Skin and Mucous Membrane: The color of the skin and the mucous membrane becomes pale. And skin loses elasticity and becomes thin and dry.
Cardiovascular System: Increase in heart rate and cardiac output. The heart is dilated, and cardiac murmurs are produced.
Respiratory System: Increase in rate of respiration and difficulty in breathing.
Digestive System: Constipation, gastrointestinal mucosal abnormalities, vomiting, and nausea.
Neuromuscular System: Increased sensitivity to cold, lack of concentration, restlessness, and vertigo.
Reproduction System: In females, the menstrual cycle is disturbed.
Two methods can classify anemia. They are:
The morphological classification depends upon the size and color of red blood cells.
Normocytic Normochromic Anemia: The size and color of red blood cells are normal, but the number of red blood cells is less.
Macrocytic Normochromic Anemia: Red blood cells are larger in size, and their color is normal, but their count is less.
Macrocytic Hypochromic Anemia: Red blood cells are larger. As a result, the mean corpuscular hemoglobin concentration is less. So the cells are pale in color.
MicrocyticHypochromic Anemia: Red blood cells are smaller in size with fewer colors.
Based on etiology, anemia is divided into five types:
Hemorrhagic Anemia: Hemorrhagic anemia refers to excessive blood loss. It occurs in acute and chronic conditions.
Acute Hemorrhage: Acute hemorrhagic anemia refers to the sudden loss of blood in a large quantity. For example - an accident.
Chronic Hemorrhage: Chronic hemorrhage is the loss of blood by internal or external bleeding over a long time. Examples - include peptic ulcers, purpura, and hemophilia.
Hemolytic Anemia: Hemolysis means the breakdown of Red blood cells. Anemia is caused by uncontrolled hemolysis, which is not reimbursed by the production of red blood cells. It is classified into two types.
Extrinsic Hemolytic Anemia: Extrinsic hemolytic anemia is the destruction of red blood cells by external factors. Red blood cells are hemolyzed by factors such as antibodies, chemicals, and drugs. The common cause of external hemolytic anemia include liver failure, renal disorders, burns, and autoimmune diseases such as rheumatoid arthritis and ulcerative colitis.
2. Sickle Cell Anemia:
Sickle cell anemia is a type of inherited disease that has sickle-shaped red blood cells. It is due to abnormal hemoglobin called hemoglobin S. In this type of anemia, the erythrocytes (red blood cells) attain a sickle shape and become more fragile, leading to hemolysis. These sickle-shaped cells get logged in the capillaries, which can cause obstruction in the blood flow and decrease the supply of oxygen to the parts of the body.
Thalassemia is a genetic disorder that refers to abnormal hemoglobin. In normal hemoglobin, the number of polypeptide chains is equal; in thalassemia, the production of these chains becomes imbalanced because of the defective synthesis of globin genes. Thalassemia is of two types -
- Alpha-Thalassemia - Alpha-thalassemia occurs in fetal life in which the alpha chains are less absent or abnormal.
- Beta-Thalassemia - Beta-thalassemia is very common. In this, the beta chain is less in number, absent, or abnormal with an excess of alpha chains.
4. Nutrition Deficiency Anemia:
Anemia refers to the deficiency of a nutritive substance necessary for erythropoiesis (red blood cell production) and is called nutrition deficiency anemia. The substance which is important for red blood cell production is iron, proteins, and vitamins like vitamin C, B12, and folic acid.
5. Iron Deficiency Anemia:
Iron deficiency anemia is caused due to insufficient absorption of iron for hemoglobin synthesis. Clinical features of iron deficiency anemia include -
- Atrophy of papillae in the tongue.
- Dysphagia (difficulty in swallowing).
6. Protein Deficiency Anemia:
Protein deficiency anemia refers to a deficiency of protein in the synthesis of hemoglobin. This leads to macrocytic and hypochromic red blood cells.
7. Pernicious Anemia or Addison's Anemia:
Pernicious anemia is anemia due to a deficiency of vitamin B12. It is due to autoimmune destruction of the gastric mucosa. This results in decreased production of intrinsic factors and poor absorption of vitamin B12. Vitamin B12 is a maturation factor for red blood cells; this leads to larger red blood cells and immaturity with almost normal or slightly low hemoglobin levels.
Clinical features of pernicious anemia -
- Females are more susceptible than males.
- Other autoimmune disorders.
8. Megaloblastic Anemia:
Megaloblastic anemia refers to the deficiency of folic acid. Folic acid plays an important role in the maturation of red blood cells because of its deficiency. The red blood cells remain immature and can not perform their regular functions.
9. Aplastic Anemia:
Aplastic anemia refers to red bone marrow disorders. The reduction of red bone marrow leads to the accumulation of fatty tissues. Bone marrow disorders occur in the following conditions -
- Presence of bacterial toxins, quinine, gold salts, radium, etc.
In aplastic anemia, the red blood cells are normocytic and normochromic.
10. Anemia of Chronic Diseases:
Anemia of chronic diseases is the second most common type of anemia. It is characterized by the short lifespan of red blood cells, caused by a disturbance in iron metabolism or insufficiency in erythropoiesis. Red blood cells are normocytic and normochromic. Common causes of anemia of chronic diseases are:
- Chronic infections like tuberculosis.
11. Polycythemia Vera:
Polycythemia is the abnormal increase in the red blood cell count. It is characterized by a persistent increase in red blood cell count above 14 million/cu mm of blood. It is related to the rise in white blood cell count. It is seen in myeloproliferative disorders like malignancy.
Thrombocytopenia is caused due to a decrease in platelet count that leads to thrombocytopenia purpura. It occurs in the following conditions:
- Aplastic and pernicious anemia ( when body stops making new red blood cells).
- Splenomegaly (spleen enlargement).
- Purpura (a bleeding problem associated with small blood clots).
Thrombocytosis refers to an increase in platelet count. It occurs in the following conditions:
Thrombocythemia is a condition with a persistent and abnormal increase in platelet count. It occurs in the following conditions:
Hemophilia is an inherited blood disorder featured by prolonged clotting time and bleeding time does not get affected. It occurs due to the lack of formation of a prothrombin activator. The formation of the prothrombin activator is affected due to the deficiency of factors VIII (Antihemophilic factor), IX (Christmas factor), or XI (Plasma thromboplastin antecedent).
Classification of hemophilia:
Hemophilia A - It refers to the deficiency of factor VIII (Antihemophilic Factor). It is the most common hemophilia; around 85 percent of people are affected by hemophilia A.
Hemophilia B - It refers to the deficiency of factor IX (Christmas factor). Seen in around 15 percent of people affected by hemophilia B.
Hemophilia C - It refers to factor XI deficiency (plasma thromboplastin antecedent factor). It is a sporadic bleeding disorder.
Purpura is defined as bleeding disorders featured by prolonged bleeding time and standard clotting time. The main character of this disease is continuous bleeding under the skin from ruptured capillaries. It leads to purpuric spots, small hemorrhagic spots present beneath the skin.
17. Von Willebrand Disease:
Von Willebrand Disease is a bleeding disorder that leads to excessive bleeding. It is due to the deficiency of the Von Willebrand factor, which is a protein secreted by the endothelium of the blood vessels. The deficiency of the factor suppresses platelet adhesion, which results in excessive bleeding.
Thrombosis is a blood clotting disorder that refers to the coagulation of blood inside the blood vessels and the formation of a thrombus.
Causes of thrombosis are:
- Roughened endothelial lining.
Leukocytosis is the increase in total leukocyte (white blood cells) count.
It occurs in conditions like:
Leukopenia is caused by the deceased in the white blood cell count.
It occurs in conditions like:
Hematological disorders can be caused by different internal and external factors. Blood investigation is an initial step in every treatment, so it is essential to understand the blood and its disorders. In addition, knowledge and awareness about hematological disorders may facilitate timely detection and medication.