CBC

CBC Interpretation

Introduction to CBC

Definition and Components

A Complete Blood Count (CBC) is a laboratory test that evaluates the cellular components of blood. It provides crucial diagnostic and monitoring insights for various hematologic and systemic disorders. The major components include:

1. Red Blood Cell (RBC) Parameters

   • RBC count
   • Hemoglobin (Hgb)
   • Hematocrit (Hct)
   • RBC indices: MCV, MCH, MCHC, RDW

2. White Blood Cell (WBC) Parameters

   • Total WBC count
   • Differential WBC count (Neutrophils, Lymphocytes, Monocytes, Eosinophils, Basophils)

3. Platelet Parameters

   • Platelet count
   • Mean Platelet Volume (MPV)
   • Platelet Distribution Width (PDW)

Indications and Clinical Uses

• Anemia Evaluation
• Infection and Inflammation (WBC abnormalities)
• Bone Marrow Disorders (Leukemia, Myelodysplastic Syndromes)
• Clotting and Bleeding Disorders (Thrombocytopenia, Thrombocytosis)
• Systemic Conditions (Liver disease, Renal failure, Autoimmune disorders)

CBC/CBP report

Red Blood Cells (Erythrocytes) & Indices

1. RBC Count

• Measures the number of circulating red blood cells (millions per microliter of blood).
• Normal range:
  • Men: 4.7–6.1 million/µL
  • Women: 4.2–5.4 million/µL
  • Children: 4.1–5.5 million/µL
• Elevated RBC count (Polycythemia): Dehydration, COPD, high altitude, polycythemia vera
• Low RBC count (Anemia): Blood loss, hemolysis, bone marrow failure

2. Hemoglobin (Hgb) & Hematocrit (Hct)

Hemoglobin (Hgb)

• The oxygen-carrying protein in RBCs
• Normal range:
  • Men: 13.8–17.2 g/dL
  • Women: 12.1–15.1 g/dL

Hematocrit (Hct):

• Measures the proportion of blood volume occupied by RBCs
• Normal range:
  • Men: 42–52%
  • Women: 37–47%

3. Red Cell Indices

Mean Corpuscular Volume (MCV) – Size of RBCs

• Normal: 80–100 fL
• Microcytic Anemia (MCV < 80 fL) → Iron deficiency, thalassemia
• Macrocytic Anemia (MCV > 100 fL) → B12/Folate deficiency, alcoholism

Mean Corpuscular Hemoglobin (MCH)

• Normal: 27–31 pg/cell
• Low: Hypochromic anemias
• High: Macrocytosis

Mean Corpuscular Hemoglobin Concentration (MCHC)

• Normal: 32–36 g/dL
• Low: Hypochromic anemias
• High: Spherocytosis

Red Cell Distribution Width (RDW) – RBC Size Variation

• Normal: 11.5–14.5%
• Increased RDW: Iron deficiency, mixed anemia types

4. Reticulocyte Count (Bone Marrow Activity Indicator)

• Normal: 0.5–2.5%
• High: Hemolysis, blood loss
• Low: Bone marrow suppression

White Blood Cells & Differential Count

1. Total WBC Count

• Normal: 4,000–11,000/µL
• Leukocytosis (>11,000/µL): Infection, leukemia, stress
• Leukopenia (<4,000/µL): Bone marrow suppression, viral infections

2. Differential WBC Count

• Neutrophils (55–70%) – Bacterial infections
• Lymphocytes (20–40%) – Viral infections, chronic conditions
• Monocytes (2–8%) – Chronic infections, TB
• Eosinophils (1–4%) – Allergies, parasitic infections
• Basophils (<1%) – Allergies, chronic inflammation

3. Neutrophil-to-Lymphocyte Ratio (NLR) in Disease Prognosis

• Higher NLR: Predicts worse prognosis in infections, cancer

Platelet Count & Function

1. Platelet Count

• Normal: 150,000–450,000/µL
• Thrombocytosis (>450,000/µL): Inflammation, malignancy
• Thrombocytopenia (<150,000/µL): ITP, DIC, leukemia

2. Platelet Indices

• Mean Platelet Volume (MPV): 7.5–11.5 fL
• Platelet Distribution Width (PDW): Increased in platelet disorders

Peripheral Blood Smear Correlation

• RBC Morphology: Target cells (Thalassemia), Schistocytes (DIC)
• WBC Abnormalities: Blast cells (Leukemia), Toxic granulation (Infection)
• Platelet Morphology: Giant platelets (ITP), Clumping

Interpretation in Specific Clinical Scenarios

1. Infection & Inflammation Patterns

• High neutrophils (Bacterial), High lymphocytes (Viral)

2. Anemia Workup

• Microcytic: Iron deficiency
• Normocytic: Chronic disease
• Macrocytic: B12/Folate deficiency

3. Bone Marrow Disorders

• Leukemia, Myelodysplasia

4. Platelet Disorders

• ITP, TTP, DIC

Conclusion & Further Workup

• Additional Tests: Bone marrow biopsy, Iron studies, Vitamin B12/Folate
• Role in Disease Monitoring: Chronic anemia, leukemia