Unit 5.7 CBC

Definition: A complete blood count (CBC) with differential, also known as a blood differential test, is a laboratory test that provides detailed information about blood cells and the immune system.
What it Measures:
- Counts total number of:
- Red blood cells (RBCs)
- White blood cells (WBCs)
- Platelets
- Counts specific types of white blood cells:
- Neutrophils
- Lymphocytes
- Monocytes
- Eosinophils
- Basophils
Uses:
- Diagnosis of conditions such as:
- Anemia
- Infections
- Allergies
- Certain cancers
- Monitoring side effects of certain drugs.
Reporting:
- Test report includes levels of each type of blood cell which helps in interpreting results and identifying abnormalities.

Normal Range: 5,000 – 10,000 cells/mcL.
Main Function: Fight infection.
Conditions:
- Leukopenia: Low WBC count.
- Causes include:
  - Autoimmune diseases
  - Medications (immunosuppressive agents, mental health medications, chemotherapy)
  - Severe illness, e.g., sepsis, cancers, lupus, HIV/AIDS, radiation therapy.
- Leukocytosis: High WBC count.
- Causes include:
  - Infection
  - Inflammation
  - Leukemia
  - Extreme stress
  - Medication side effects.

Neutrophils (40-70%):
- Function: Fights bacterial infections.
Lymphocytes (20-40%):
- Function: Fights viral infections.
Monocytes (4-13%):
- Function: Fights infection and foreign substances.
Eosinophils (1-5%):
- Role: Allergic response and combating parasite infections.
Basophils (0.1-2%):
- Role: Involved in inflammatory conditions and allergy responses.

Normal Range: 4.5-5.5 million/mcL.
- Also referred to as erythrocytes or red blood corpuscles.
Main Function: Transport oxygen throughout the body and deliver carbon dioxide to the lungs for exhalation.
Conditions:
- Anemia: Low red blood count.
- Polycythemia: High red blood count, often associated with blood cancer when the bone marrow produces too many RBCs.
Key Components:
- Hemoglobin:
- Definition: Protein in RBCs that carries oxygen.
- Normal Levels:
  - 12–16 g/dL (women)
  - 14–18 g/dL (men)
- Hematocrit:
- Definition: Measure of the proportion of blood volume that is made up of RBCs.
- Normal Levels:
  - 37 – 47% (women)
  - 42 – 52% (men).

Definition: Provides additional information on RBC size and hemoglobin status, particularly useful in cases of anemia (iron deficiency, vitamin B12, or folate deficiency).
Indices:
- Mean Corpuscular Volume (MCV):
- Definition: Size of RBCs.
- Normal Range: 80-100 femtoliters (fL).
- Mean Corpuscular Hemoglobin (MCH):
- Definition: Amount of hemoglobin in each RBC.
- Normal Range: 27-33 picograms (pg) per cell.
- Mean Corpuscular Hemoglobin Concentration (MCHC):
- Definition: Concentration of hemoglobin in a RBC.
- Normal Range: 33-36 grams per deciliter (g/dL).
- Red Cell Distribution Width (RDW):
- Definition: Variation in RBC size.
- Normal Range: 11-15%.

Normal Range: 150,000–400,000 cells/mcL.
Main Function: Contributes to blood clotting when bleeding occurs.
Mean Platelet Volume (MPV):
- Definition: Average size of platelets in the blood.
- Normal Range: 7-10 femtoliters (fL).
Conditions:
- Thrombocytopenia: Low platelet count, increasing bleeding risk.
- Causes: Bone marrow issues, chemotherapy, viral infections.
- Thrombocytosis: High platelet count, increasing clotting risk.
- Causes: Leukemia, inflammatory diseases, acute blood loss.

Red Blood Cells (Erythrocytes):
- Accounts for approximately 45% of total blood volume.
- Functions: Transport oxygen to tissues and carry away carbon dioxide.
Platelets (Thrombocytes):
- Cell fragments without a nucleus.
- Functions: Assist in blood clotting by adhering to vessel walls and plugging ruptured sites.
Monocyte:
- Makes up 3-8% of total WBCs.
- Largest WBC type, with a kidney- or horseshoe-shaped nucleus.
- Functions: Phagocytosis (engulfing and removing pathogens and debris).
Lymphocyte:
- Comprises 20-25% of total WBCs.
- Range of sizes and agranular nuclei.
- Types include T-cells, B-cells, and natural killer cells; vital for immune response.
Neutrophil:
- Contains granular WBCs with lobed nuclei.
- Main functions include phagocytosis.
Basophil:
- Comprises 0.5-1% of WBCs.
- Contains lobed nuclei, releases heparin, histamine, and serotonin during allergic reactions.
Eosinophil:
- Makes up 2-4% of WBC population.
- Lobed nuclei connected by thick strands; combats histamines in allergic responses.

WBC (Leukocyte):
- Functions: Fights infection.
Neutrophil:
- Essential in preventing or limiting bacterial infections via phagocytosis.
Monocyte:
- Enters tissues as macrophages; highly phagocytic particularly against fungi; plays immune surveillance roles.
Eosinophil:
- Engaged in allergic reactions and digests foreign proteins.
Basophil:
- Integral part of hypersensitivity reactions; releases histamine.
Lymphocyte:
- Critical component of the immune system; T lymphocytes manage cell-mediated immunity while B lymphocytes form antibodies.
Red Blood Cell (Erythrocyte):
- Carries hemoglobin for oxygen delivery to tissues with a lifespan of approximately 120 days.
Platelet (Thrombocyte):
- Life span averages around 10 days; provides basis for coagulation to maintain hemostasis.

Elevated WBCs (Leukocytosis):
- Indicates conditions like infection, inflammation, necrosis, malignancy, hyperleukocytosis, and various medications.
Low WBCs (Leukopenia):
- Indicates infections, cytotoxic drugs, malignancy, autoimmune diseases, or nutritional deficiencies.
High RBC Count:
- Considered in polycythemia vera, chronic hypoxia, or dehydration.
Low RB Count:
- Typically indicates anemia.
Various underlying issues assessed with RBC indices correlated with hemoglobin and hematocrit values, including different forms of anemia (e.g., iron deficiency, vitamin B12 deficiency).
Thrombocytopenia and Thrombocytosis:
- Addressed through assessing platelet counts in context with overall health parameters and related conditions.