Diseases of Blood: Anemia

Diseases of Blood

1. Basic Concepts & Definitions

• Anemia:

• Introduction: A condition characterised by a decrease in hemoglobin (Hb) levels or total Red Blood Cell (RBC) count, resulting in reduced oxygen delivery to tissues.

Definition: A blood disorder marked by a decreased oxygen-carrying capacity of the blood.

Normal Haemoglobin Levels:

• Males: 14-18 \text{ g/dL}

• Females: 12-15 \text{ g/dL}

Types of Anemia & Etiology

1. Iron Deficiency Anemia:

   • The most common type of anemia, caused by inadequate iron supply needed for hemoglobin production in the bone marrow.

   • Causes: Low dietary iron intake, chronic blood loss, and pregnancy.

2. Megaloblastic Anemia (Vitamin $B_{12}$ / Folate Deficiency):

   • Caused by a lack of Vitamin $B_{12}$ or Folic acid, which are essential for normal DNA synthesis and RBC maturation, leading to defective RBC production.

3. Aplastic Anemia:

   • A severe, life-threatening condition where bone marrow stem cells fail to produce sufficient blood cells (RBCs, WBCs, and platelets).

   • The bone marrow becomes hypocellular and is replaced by fatty tissue.

   • Causes: Autoimmune disorders, exposure to toxic chemicals or radiation.

4. Sickle Cell Anemia:

   • A genetic hemolytic disorder characterized by the production of abnormal hemoglobin (HbS).

   • Deoxygenation causes RBCs to become rigid and crescent/sickle-shaped, leading to hemolysis, vascular occlusion, and premature destruction of RBCs.

5. Hemolytic Anemia:

   • A condition where RBCs are destroyed faster than they can be produced by the bone marrow.

   • RBC lifespan drops from the normal $120 \text{ days}$ down to $30-40 \text{ days}.

Etiology:

• Intrinsic (Hereditary): Red cell membrane defects, Sickle cell anemia, enzyme deficiencies.

• Extrinsic (Acquired): Autoimmune destruction, infections (e.g., Malaria), toxic chemicals or drugs (e.g., Penicillin).

 Clinical Manifestations: Diseases of Blood: Anemia

• General Symptoms (Hypoxia):

  • Fatigue, generalized weakness, and tiredness

  • Dizziness, shortness of breath, and headaches

  • Muscle pain and poor concentration

• Integumentary Symptoms:

  • Cold hands and feet

  • Pallor (pale or yellowish skin, mucous membranes, and nail beds)

• Cardiovascular & Systemic Manifestations:

• Tachycardia, heart palpitations, dyspnea, and heart failure

• Loss of appetite, diarrhea, numbness, tingling sensations, and muscle cramps

4. Diagnostic Evaluation & Management

• Diagnostic Tests:

  • Physical examination and detailed clinical history

  • Hemoglobin concentration and Complete Blood Count (CBC)

  • Hematocrit (Hct) measurement and serum vitamin levels ($B_{12}$, Folate, Iron)

  • Bone marrow aspiration

• Complications:

  • Severe debilitating fatigue

  • Pregnancy complications (e.g., premature birth)

  • Heart failure and mortality

• Medical Management:

  • Supplemental oxygen therapy

  • Intravenous fluids and nutritional replacement

  • Packed Red Blood Cell (PRBC) transfusion

5. Coagulation & Clotting Factors

Secondary hemostasis involves clotting factors, the deficiency or dysfunction of which leads to bleeding disorders.

The 13 Blood Clotting Factors:

1. Factor I: Fibrinogen

2. Factor II: Prothrombin

3. Factor III: Thromboplastin

4. Factor IV: Calcium ions ($Ca^{2+}$)

5. Factor V: Proaccelerin / Labile factor

6. Factor VI: (Unassigned / Inactive)

7. Factor VII: Proconvertin / Stable factor

8. Factor VIII: Antihemophilic Factor A (AHF-A)

9. Factor IX: Christmas Factor / AHF-B

10. Factor X: Stuart-Prower factor

11. Factor XI: Plasma thromboplastin antecedent

12. Factor XII: Hageman factor

13. Factor XIII: Fibrin stabilizing factor

6. Bleeding Disorders

A. Hemophilia

• Definition: An inherited X-linked recessive disorder caused by a deficiency in specific clotting factors, causing impaired blood clotting and prolonged bleeding.

• Genetics: X-linked inheritance (passed from carrier mothers to sons; primary impact is on males).

• Types:

  • Hemophilia A: Deficiency of Factor VIII; four times more common than Hemophilia B.

  • Hemophilia B: Deficiency of Factor IX (Christmas disease).

B. Von Willebrand Disease (VWD)

• The most common inherited bleeding disorder, caused by a deficiency or impairment of Von Willebrand Factor (VWF).

• Functions of VWF:

• Promotes platelet adhesion to injured vascular endothelium.

• Serves as a carrier protein for Factor VIII, protecting it from premature degradation.

7. Signs, Symptoms & Management of Bleeding Disorders

• Symptoms:

• Epistaxis (frequent nosebleeds), mucosal bleeding, bleeding gums

• Hematuria (blood in urine) and hematochezia (blood in stool)

• Hemarthrosis: Bleeding into joint spaces

• Hematomas: Soft tissue hemorrhages

• Heavy menstrual bleeding (menorrhagia) and postpartum hemorrhage in females

Management:

• Factor replacement therapy (Prophylactic or On-Demand)

• Desmopressin (DDAVP) therapy

• Physical therapy for joint care

• Avoidance of NSAIDs/Aspirin to prevent aggravation of bleeding