Thrombocytes : Pathophysiology

• Thrombocytopenia

  - low platelet count: 150 x 10^9 (150,000/mm^3)

  - due to a reduced platelet production rate or increased destruction rate

  ☆ Spontaneous bleeding
• Thrombocytopenia: Spontaneous bleeding

  doesn't usually occur unless the count falls below 30 x 10^9/L (30,000/mm^3)
• Thrombocytopenia: Reduced Production or Increased Destruction: Examples (2)

  1. Autoimmune Thrombocytopenic Purpura

  2. Disseminated Intravascular Coagulation
• Autoimmune Thrombocytopenic Purpura (ITP)

  - children and young adults

  - due to viral infection: e.g., Measles
• Purpura

  - significant feature of Autoimmune Thrombocytopenic Purpura

  - hemorrhages into the skin

  - varied size: pinpoints to large blotches
• Antiplatelet antibodies Formation

  - coat platelets

  - leads to platelet destruction & elimination from circulation
• Autoimmune Thrombocytopenic Purpura (ITP): Severity Range

  mild bleeding into the skin to severe hemorrhage
• Autoimmune Thrombocytopenic Purpura (ITP): Very low platelet count indicates (3)

  1. Severe bruising

  2. Hematuria

  3. Gastrointestinal or intracranial hemorrhages
• Vitamin K Deficiency: Types (2)

  1. Hemorrhagic disease of the newborn

  2. Deficiency in adults
• Vitamin K

  - required by the liver

  - synthesis of many clotting factors

  - deficiency predisposes to abnormal clotting

  - fat-soluble
• Hemorrhagic disease of the newborn

  - limited stores of vitamin K

  - cause bleeding in the first few months of life
• Vitamin K Deficiency in adults

  bile salts: required in the colon for its absorption
• Vitamin K Deficiency in adults: A Complication in (3)

  1. liver disease

  2. prolonged obstruction of the biliary tract

  3. Other disease where fat absorption is impaired, e.g. celiac disease
• Disseminated Intravascular Coagulation (DIC)

  - abnormal blood clotting in blood vessels, affecting normal coagulation

  - coagulation system is inappropriately activated

  - consumption of clotting factors and platelets
• Disseminated Intravascular Coagulation (DIC): Effects (3)

  1. Intravascular clots formation

  2. Fibrin deposition in the tissues

  3. Tendency to hemorrhage
• Disseminated Intravascular Coagulation (DIC): A Complication in (6)

  1. Severe infections

  2. Severe trauma

  3. Premature separation of the placenta

  4. Acute pancreatitis

  5. Advanced cancer

  6. Transfusion of very large volumes of blood
• Congenital Hemorrhagic Disorders (2)

  1. Hemophilia

  2. von Willebrand disease
• Hemophilia

  - inability to produce 1 or more clotting factor

  - sex-linked recessive disease; on X chromosome
• Hemophilia: Faulty genes code (2)

  1. Factor VIII

  2. Christmas factor
• Hemophilia in Women

  Women are carriers; their blood clotting is normal
• Hemophilia: Bleeding Episodes

  - repeated episodes of severe and prolonged bleeding at any site, even in the absence of trauma

  - recurrent bleeding into joints: common
• Hemophilia: Types (2)

  1. Hemophilia A

  2. Hemophilia B
• Hemophilia A

  factor VIII: abnormal, less biologically active than normal
• Hemophilia B

  - factor IX: deficient

  - thromboplastin (factor III) deficiency

  - aka Christmas disease

  - less common
• Inheritance of a Sex-Linked Disease

  From Mother:

  - Daughter: carrier

  - Son: Hemophilia

  
  

  From Father

  - Daughter: carrier

  - Son: No Hemophilia
• von Willebrand disease

  - factor VIII deficiency

  - most common inherited bleeding disease

  - occur equally in males and females

  - not sex-linked