Understanding Anemia: Types, Symptoms, and Causes

Anemia

• Anemia is a physiologic manifestation
• It results in reduced oxygen-carrying capacity, leading to hypoxemia.
• Symptoms can vary based on the severity and the body’s ability to compensate.
• Common symptoms include fatigue, weakness, dyspnea, and pallor.
• It involves a reduction in the total number of erythrocytes in circulating blood
• It also concerns the quality or quantity of hemoglobin.
• Causes can include:
  • Impaired erythrocyte production
  • Acute or chronic blood loss
  • Increased erythrocyte destruction
  • A combination of all these factors

Anemia Classification Using MCV Value

• Helps classify different types of anemia
• Based on the mean corpuscular volume (MCV)
• MCV is a measure of the average size of red blood cells (measured in femtoliters)
• Size is identified by terms ending in "-cytic" (macrocytic, microcytic, normocytic)
• Hemoglobin content is identified by terms ending in "-chromic" (normochromic, hyperchromic, hypochromic)

Microcytic Anemia

• The MCV is less than 80 fl
• Involves small red blood cells
• Caused by a lack of iron in hemoglobin (hypochromic)
• It can also be caused by lack of hemoglobin production (normochromic)
• Examples: iron-deficiency anemia and thalassemia

Normocytic Anemia

• An MCV is between 80-100 fl
• Occurs with normal red blood cell size.
• Examples: anemia of chronic disease, aplastic anemia, and hemolytic anemia.

Macrocytic Anemia

• An MCV is greater than 100 fl.
• Involves large red blood cells
• Examples: Vitamin B12 deficiency anemia and folate deficiency anemia
• Macrocytic anemia can coexist with microcytic or normocytic anemia.

Normocytic Anemia

• Often grouped by whether reticulocytes are increased vs. decreased and hemolytic vs. non-hemolytic
• Increased reticulocytes means the body is trying to make new RBCs.

Macrocytic Anemia

• It involves large size caused by defects in RBC maturation or a disproportionate number of reticulocytes (reticulocytosis).
• Has 2 categories:
  • Megaloblastic anemia refers to the large-sized cells that are caused by defects in DNA synthesis in RBCs.
  • Non-megaloblastic anemia refers to the large size caused by RBC developmental issues.

Anemias of Blood Loss

• Acute blood loss: Posthemorrhagic anemia
• Chronic blood loss:
  • Anemia can occur if the blood loss exceeds bone marrow replacement capacity.
  • Iron deficiency anemia can occur.

Aplastic and Hemolytic Anemias

• Aplastic anemia: Body is not making enough RBCs due to hematopoietic failure or bone marrow aplasia, Reduced production of mature cells, Pancytopenia- reduction in RBC, WBC, platelets
• Hemolytic anemia: Premature accelerated destruction of erythrocytes

Myeloproliferative RBC Disorders

• Polycythemia involves the overproduction of red blood cells.
• Relative polycythemia (dehydration) occurs when fluid loss results in relative increases of red cell counts and Hgb and Hct values.
• Hereditary hemochromatosis:
  • Involves iron overload disorder, an autosomal recessive disorder of iron metabolism
  • Exhibits mutations in Hepcidin,the protein that governs iron regulation
  • From excessive storage of iron in the liver, skin, pancreas, heart, joints, and testes
  • It may or may not have polycythemia.

Alterations of Leukocyte Function

• Quantitative disorders involve increases or decreases in cell numbers due to bone marrow disorders or premature destruction of cells
• It is also caused by a response to infectious microorganism invasion.
• Qualitative disorders involve disruptions of leukocyte function, causing phagocytes or lymphocytes to lose their abilities.

Quantitative Alterations of Leukocytes

• Leukocytosis:
  • High leukocyte count
  • It is a normal protective physiologic response to physiologic stressors, such as infectious microorganisms.
• Leukopenia:
  • Low leukocyte count that is not normal or beneficial, and predisposes a patient to infections.

Quantitative Alterations of Granulocytes

• Granulocytosis (neutrophilia):
  • Increase in granulocytes
  • Evident in the first stages of an infection or inflammation
• Immature neutrophils are released if the need for neutrophils increases beyond the supply.
• Neutropenia:
  • Reduction in circulating neutrophils
    • Caused by prolonged severe infection
    • Decreased production
    • Reduced survival
    • Abnormal neutrophil distribution and sequestration Chemotherapy can cause granulocytopenia (severe neutropenia) or agranulocytosis (absence of granulocytes).

Quantitative Alterations of Granulocytes

• Eosinophilia involves an increase in circulating eosinophils caused by hypersensitivity reactions
  • Also allergic disorders and parasitic invasions
• Eosinopenia involves a decrease in circulation numbers of eosinophils, caused by migration of cells to inflammatory sites.
• Basophilia involves an increase in circulating basophils caused by response to inflammation and hypersensitivity reactions.
• Seen in myeloproliferative disorders
• Basopenia involves a decrease in circulating numbers of basophils
  • Occurs in acute infections, hyperthyroidism, ovulation, pregnancy, and long-term steroid therapy.

Quantitative Alterations of Monocytes

• Monocytosis involves an increase in circulating monocytes
  • It is often transient and unrelated to dysfunction of monocyte production.
  • It usually occurs with neutropenia in later stages of infections
  • This occurs when monocytes are needed to phagocytize organisms and debris.
• Monocytopenia involves a decrease in circulating monocytes, but is very rare.

Quantitative Alterations of Lymphocytes

• Lymphocytosis involves an increase in the number or proportion of lymphocytes
  • Caused by acute viral infections, particularly caused by Epstein-Barr virus (EBV).
• Lymphocytopenia involves a decrease in the number of circulating lymphocytes
  • Caused by abnormal production due to immune deficiencies or caused by destruction by drugs, viruses, or radiation.

Lymphadenopathy

• Involves enlarged lymph nodes that become palpable and tender.
• Can be localized, such as drainage of an inflammatory lesion located near the enlarged node.
• Can be generalized: occurs in the presence of infections, autoimmune diseases, or disseminated malignancy.

Plasma Cell Malignancy

• Multiple Myeloma (MM) is a malignant proliferation of plasma cells that infiltrate bone marrow and aggregate into tumor masses in the skeletal system, causing lytic bone lesions
• Manifestations include hypercalcemia, renal failure, anemia, and immune abnormalities, preceded by monoclonal gammopathy of undetermined significance.

Alterations of Splenic Function

• Splenomegaly: Enlargement of spleen, may or may not be pathologic.
  • Congestive: Red pulp
  • Infiltrative: White pulp
  • Infectious: White pulp
• Hypersplenism: Overactivity of spleen that causes anemia.

Blood Clotting Process

• Hemostasis relies on major components to function normally
• These include the blood vessels, platelets and plasma coagulation factors.

Quantitative Disorders of Platelets

• Thrombocytopenia involves a decrease in the number of circulating platelets.
• Thrombocythemia involves an increase in the number of circulating platelets.

Impaired Hemostasis

• It is defined as an inability of coagulation and stable fibrin clot.
• Vitamin K deficiency:
  • Vitamin K is necessary for synthesis and regulation of prothrombin
  • Vitamin K is necessary for the procoagulant factors (VII, XI, X) and proteins C and S (anticoagulants).
• Liver disease:
  • Hepatic cells produce most factors involved in hemostasis
  • Damage causes production of fewer clotting factors

Thromboembolic Disorders

• Thrombus: stationary clot attached to vessel wall.
  • Arterial or venous thrombi
  • Virchow triad:
    • Injury to vessel
    • Abnormal blood flow
    • Hypercoagulopathy
• Hereditary thrombophilias: mutations in coagulation
• Embolus: Unattached mass circulating within bloodstream.

Acquired Disorders of Erythrocytes (Children)

• Iron deficiency anemia (IDA)
  • It is the most common nutritional disorder of infancy and childhood.
  • It is caused by lack of iron intake, problems with iron absorption, blood loss, and increased iron requirements.
• Hemolytic disease of the fetus and newborn (erythroblastosis fetalis)
  • Maternal antibody directed against fetal antigens
  • Rh incompatibility (most common), ABO incompatibility, or other RBC antigen.
  • It can be manifested by anemia, hyperbilirubinemia, neonatal jaundice, or bilirubin encephalopathy.

Inherited Disorders of Erythrocytes

• Sickle cell disease: Disorders characterized by the presence of hemoglobin S.
• Deoxygenation and dehydration cause Hb S to stretch and elongate, forming a sickle shape.
• It can result in vaso-occlusive crisis (thrombotic crisis).
• It may also result in aplastic crisis (not enough red blood cells) or sequestration crisis (red blood cells retained in spleen).
• Can also result in hyperhemolytic crisis(increased hemolysis).

Inherited Hemorrhagic Disease

• Hemophilias: Serious bleeding disorders that involve mutations in coagulation factors.
• Types:
  • Hemophilia A: factor VIII deficiency
  • Hemophilia B: factor IX deficiency
  • Hemophilia C: factor XI deficiency

Antibody-Mediated Hemorrhagic Disease

• Primary immune thrombocytopenia is the most common platelet consumption disorder.
• It is defined by a platelet destruction rate that exceeds production.
  • 70% of cases occur after a viral disease, with a typical onset at 1-6 years old.
  • Manifested by bruising and petechial rash.

Leukemia

• Cancer of blood-forming tissues.
  • Most common cancer in children.
    • Acute lymphoblastic leukemia (ALL): acute myelogenous leukemia (AML).