10- Basic CBC



Components Measured

The CBC test measures essential cellular components in the blood, including:

  • White Blood Cells (WBCs): Key players in the immune response.

  • Red Blood Cells (RBCs): Critical for transporting oxygen and carbon dioxide.

  • Platelets (PLTs): Essential for blood clotting and wound healing.

Purpose of CBC Test

  • Diagnosis: The CBC aids in the diagnosis of a wide array of conditions, including anemia, infection, clotting disorders, and more.

  • Monitoring Treatment: Regular CBC tests help evaluate the effectiveness of ongoing treatments, especially in patients undergoing chemotherapy or other interventions that affect blood components.

  • Evaluation of Overall Health: A CBC provides a snapshot of a patient's health, informing about various bodily functions and potential health issues.

  • Rule Out Conditions: It can help in ruling out specific diseases or disorders, facilitating timely interventions.

  • Detect Abnormalities: The test identifies irregularities or anomalies in blood components, prompting further investigation if necessary.

    Procedure of CBC

    • Sample Collection: Blood is typically drawn from a vein, usually in the arm.

      • Blood is collected in a labelled tube containing an anticoagulant to prevent clotting.

      • The sample is then transported to the laboratory for analysis using automated machines or manual methods.

    • Result Turnaround: Generally, results are available within 24 to 36 hours, although many labs can provide preliminary results sooner.

Components of CBC

Red Blood Cells (RBCs)

  • Function: RBCs are vital for the delivery of oxygen from the lungs to tissues and the return transport of carbon dioxide back to the lungs.

  • Typical range: 4.5 – 5.5 million cells per microliter (µL) of blood.

  • Lifespan: Approximately 120 days, after which they are removed and recycled by the spleen.

  • Count variations: Higher counts are typically found in males and newborns, which also exhibit diurnal variation based on time of day, activity level, and hydration status.

    Key Metrics for Red Blood Cells

    • Elevated levels indicate possible conditions such as chronic lung disease, liver disease, dehydration, carbon monoxide exposure, excess alcohol consumption or polycythemia vera.

    • Decrease levels: anemia, medications, bleeding, deficiencies of certain vitamins

    • Measurement range: Typically maintained between 4.5 – 5.5 million RBCs per µL.

White Blood Cells (WBC) Overview

  • Key types of WBCs include:

    • Lymphocytes: Involved in the immune response, including B cells and T cells. in viral infections, perdominant in pediatrics

    • Monocytes: Differentiate into macrophages and dendritic cells to aid in immune response.

    • Neutrophils: First responders to bacterial infection and inflammation. predominant in adults

    • Eosinophils: Play a role in allergic responses, asthma and parasitic infections

    • Basophils: Involved in inflammatory reactions, releasing histamine.

  • Normal Range: WBC count can vary based on overall health, age, and conditions.

  • Leukocytosis: increases WBC’s, full term newborns, leukemic conditions, bacterial infections, tissue damage and inflammation

WBC Levels Significance

  • Low WBC Count Causes: May result from autoimmune diseases, severe infections, bone marrow disorders, vitamin deficiencies (such as B12 or folate), and certain medications (e.g., chemotherapy).

  • High WBC Count Causes: Elevated levels may indicate infections, cancers (like leukemia), stress responses, tissue injury, or allergic reactions, pregnancy and medications

Platelets Overview

  • Function: Also known as thrombocytes, platelets play a crucial role in hemostasis by forming clots to prevent excessive bleeding during injury.

  • Normal range: 150,000 - 450,000 platelets per microliter (µL).

  • Lifespan: 1 to 2 weeks, after which they are removed from circulation by the spleen.

  • Thrombocytopenia: cancer, anemia, chemo, autoimmune diseases, infection, chronic bleeding (RISK OF INAPP CLOTTING)

  • Thrombocytosis: anemia, recovery from surgery, cancer, VIT B12 deficiency, inflammation and infection (RISK OF BLEEDING)

Hemoglobin (Hgb)

  • Function: Hemoglobin is the protein within RBCs responsible for oxygen transport; it binds oxygen in the lungs and releases it in body tissues.

  • Composition:

    • Heme: Contains iron, which binds to oxygen (red pigment characteristic).

    • Globin: The protein component that provides structural integrity to the hemoglobin molecule.

  • Normal ranges:

    • Males: 14-18 grams per deciliter (g/dL)

    • Females: 12-16 g/dL

    • Newborns typically present higher hemoglobin levels and also exhibit diurnal variation throughout the day.

CBC Indices

  • MCV (Mean Cell Volume): Indicates the average size of RBCs; a higher MCV may suggest macrocytic anemia caused by folate deficiency. Average 80-100 fL

  • MCH (Mean Cell Hemoglobin): Reflects the average amount of hemoglobin in each RBC; normal range is between 28 – 34 picograms (pg).

    • Low MCH may indicate iron-deficiency anemia.

  • MCHC (Mean Cell Hemoglobin Concentration): Represents the mean concentration of hemoglobin in a given volume of packed RBCs; ranges from 32 – 36 grams per deciliter (g/dL).

    • Classifications include:

      • Normochromic: Normal hemoglobin levels.

      • Hypochromic: Low hemoglobin levels, often associated with iron deficiency.

      • Hyperchromic: High hemoglobin levels.

Conditions Associated with WBC Counts

  • Leukocytosis: A condition characterized by elevated WBC counts that may indicate infections, tissue damage, leukemia, or inflammatory processes.

  • Lymphocyte Dominance: A predominance of lymphocytes often observed in viral infections, particularly prominent in pediatric populations.

  • Eosinophilia: An increase in eosinophils, frequently associated with allergic reactions, asthma, and parasitic infections.