Hematology

Hematology Overview

Hematology- the study of blood. The system is used to transport oxygen, waste, electrolytes, and maintains intramuscular volume. Coagulates blood, and fights infection.

  • Hematology: Study of blood and blood-forming tissues.

  • Major components include:

    • Bone marrow

    • Blood

    • Spleen

    • Lymphatic system.

Structures and Functions of Hematologic System

  • Hematopoiesis: Blood cell production. All blood starts off as hematopoietic, and then develops into myeloid cells. (T and B lymphocytes)

    • Occurs in bone marrow. The soft material that fills the central core of bones. Two types: Yellow (Adipose), and Red.

    • Produces:

      • Red blood cells (RBCs)

      • White blood cells (WBCs)

      • Platelets.

    • Develops from stem cells, which are non differentiated immature blood cells.

Bone Marrow

  • Soft material filling the central core of bones.

  • Types of bone marrow:

    • Yellow marrow: Contains adipose tissue.

    • Red marrow: Hematopoietic; involved in blood cell formation.

Blood Cell Development

  • Key stages in blood cell development include:

    • Stem cell transformation into:

      • Erythroblasts (red cells)

      • Myeloblasts (granulocytes)

      • Monoblasts (monocytes)

      • Lymphoblasts (lymphocytes)

      • Megakaryoblasts (platelets).

Blood Component Values

  • Whole Blood Composition:

    • Total body weight: 8%

    • Plasma: 55% (91% water, 7% proteins, 2% other solutes).

  • Formed Elements:

    • Platelets: 140,000 - 340,000 per cubic mm.

    • Leukocytes: 5,000 - 9,000

    • Erythrocytes: 4.2 - 6.2 million.

  • Distribution of leukocytes:

    • Neutrophils: 60%-70%

    • Lymphocytes: 20%-25%

    • Monocytes: 3%-8%

    • Eosinophils: 2%-4%

    • Basophils: 0.5%-1%.

Erythrocytes (RBCs)

  • Functions:

    • Transport O2 and CO2

    • Maintain acid-base balance.

  • Hemoglobin: Composed of iron and protein.

    • Oxyhemoglobin: oxygen bound with iron.

Thrombocytes (Platelets)

  • Functions:

    • Initiate the clotting process. They produce at the site of injury

    • Plug capillary openings.

    • Help in clot shrinkage and retraction.

  • Development begins with stem cells transforming into megakaryocytes, which fragment into platelets.

  • They must be available in enough numbers and be structurally and metabolicallly sound for blood clotting to occur.

  • Thrombopoietin partially regulates platelet production. TPO is a growth factor that acts on bone marrow to stimulate platelet production.

  • Produced in the liver, kidney, smooth muscle, and bone marrow.

  • Life span: 8-10 Days.

Hemostasis Process

  1. Vascular injury leads to vasoconstriction and subendothelial exposure.

  2. Adhesion: Platelets adhere to the exposed sites due to loss of endothelial tissue. adhesive glycoproteins from.

  3. Activation of the clotting cascade.

  4. Formation of blood clot, followed by clot retraction and dissolution.

Hemostasis Details

  • Initial Response: Vasoconstriction reduces blood leakage and provides time for platelet and clotting factor responses.

  • Clotting Cascade Activation:

    • Platelet adhesion triggers changes in platelet shape and activates binding to adhesive proteins; this leads to the release of granules that activate further clotting.

  • Clotting is initiated by:

    • Intrinsic pathway: Triggered by damage to blood vessels. Both pathways start at the same level, and end at the same place.

    • Extrinsic pathway: Triggered by tissue factor release. Activated by collagen exposure.

    • Clot retraction and dissolution

      Procoagulants

      Foster coagulation

      Anticoagulants

      Interfere with clotting

Assessment of Hematologic System

  • Subjective Data: Includes health history, medications (non prescription, heral supplements, substances, functional health patterns, and assessment of current health status. Nonprescription drugs: OTC, vitamins, herbal products, dietary

    supplements

  •  Subjective data: Functional health patterns

    Health perception–Health management pattern

     Usual and present state of health

     Demographic data

     Family history and genetically linked disorders

     High-risk behaviors

     Genetic risk alert

  • Objective Data: Physical assessment focusing on skin, lymph nodes, spleen, and liver for signs of hematological disorders (e.g., petechiae, ecchymoses).

 Subjective data: Functional health patterns

  • Nutritional–metabolic pattern

  • Weight, dietary pattern, history of cardiac or pulmonary diseases

    • Changes in skin texture, color or temperature

    • Characteristics of lumps in neck, armpits, or groin

  • Elimination pattern

  • Bleeding is significant

Subjective data: Functional health patterns

Activity–exercise pattern

Sleep–rest pattern

Fatigue not relieved by sleep should be evaluated

Subjective data: Functional health patterns

Sexuality–reproductive pattern

Menstrual history, impotence, or high-risk sexual

behaviors

Objective data:

Physical assessment

Diagnosis of hematologic disorders often requires considering presenting symptoms in context of broader clinical assessment findings and risk factors

Of particular importance are examination of skin, lymph nodes, spleen, and liver

Objective data

Physical examination

Skin assessment

Systematic head-to-toe order

Petechiae

Ecchymoses

Spider nevus- Spider Veins

Clubbing of fingers- Oxygen issue

Assessment Components

  • Health History: Previous anemia, other blood disorders, and medications.

  • Physical Examination: Skin assessment for signs of bleeding or bruising.

  • Nutritional and Cardiac Assessments: Important for evaluating anemia.

Anemias

  • Anemia leads to insufficient oxygen delivery to tissues due to:

    • Blood loss

    • Inadequate RBC production

    • Increased RBC destruction. RBC are destroyed faster than they can be replaced.

Pathophysiology of Anemias

Physiology review- Dry Mouth (Chilitis), pale conjuctiva

Amount of oxygen that reaches tissues depends on:

Available oxygen in alveoli

Diffusing surface, capacity of lungs

Number of RBCs, amount and type

of hemoglobin they contain

Ability of cardiovascular system to

transport blood and oxygen to

tissues

Blood loss

Inadequate RBC production

Increased RBC destruction

Insufficient or defective hemoglobin

within RBCs

Health history and physical exam

Laboratory data- Hemoglobin, Reticulocyte, Hematocrit

Presence of symptoms and impact of those symptoms on

patient’s life; fatigue, weakness, malaise, pain. Dry Mouth, Pale conjunctiva

Nutritional assessment

Medications

Cardiac and GI assessment- TachyCardia, Low blood viscosity leading to heart murmurs, orthostatic hypotension, hypoxia, dyspnea(SOB)

Blood loss: menses, potential GI loss

Neurologic assessment- confusions, headache, ataxia, loss of control of your body moments.

Cobalamin (Vitamin B12) Deficiency

  • Characterized by large RBCs (megaloblasts) due to impaired DNA synthesis.

  • Treatment includes parenteral or intranasal cobalamin administration, critical for preventing death in untreated individuals.

  • Caused by absence of intrinsic factor (IF)

    Insidious onset

    Begins in middle age or later

    Predominant in Scandinavians and blacks

  • Red beefy tongue, abdominal pain, nasuea and vommiting, impaired cognition, ataxia

Folic Acid Deficiency

  • Contributes to megaloblastic anemia.

  • Similar manifestations to B12 deficiency; treated with folate replacement therapy.

Aplastic Anemia

  • Characterized by pancytopenia (decreased RBCs, WBCs, and platelets).

  • Diagnosis confirmed by laboratory findings and examination of bone marrow.

  • Prognosis is poor if untreated but improved through treatments such as immunosuppressive therapy.

Thrombocytopenia

  • Reduced platelet count leading to increased bleeding risk.

  • Managed based on underlying causes; can include conditions like ITP and HIT.

Lymphomas

  • Hodgkin's Lymphoma and Non-Hodgkin's Lymphoma are prevalent lymphatic cancers characterized by different cellular abnormalities and genetic features.

  • Diagnosis and prognosis vary widely based on subtype and staging.

  • Treatment regimens include chemotherapy, targeted therapy, and monitoring for secondary cancers after treatment.

Conclusion

  • This lecture presented foundational concepts of hematology, emphasizing the vital understanding of blood cell development, hematopoiesis, and related disorders for effective assessment and management strategies in clinical practice.