HematologyInternal Medicine

Complete Blood Count (CBC)

Normal Range
WBC: 4.5-11.0 k/uL, Hb: 13.5-17.5 (M) g/dL, PLT: 150-450 k/uL
Sample Type
Whole Blood
Fasting
No
Unit
Mixed

Function

The Complete Blood Count (CBC) is a fundamental diagnostic panel that measures the various components of the blood, including red blood cells (RBCs), white blood cells (WBCs), and platelets. It provides a snapshot of the body's hematologic health and its ability to transport oxygen, fight infection, and maintain hemostasis.

Why it is Ordered

A CBC is ordered as part of routine physicals, to monitor ongoing treatments (like chemotherapy), and to diagnose symptoms such as fatigue, bruising, or fever. It is the gold standard for screening for anemia and systemic infections.

Associated Conditions

  • Anemia: Low RBC or Hemoglobin counts indicating iron deficiency, B12 deficiency, or chronic disease.
  • Infection and Inflammation: Elevated WBC counts (Leukocytosis) suggest the body is responding to pathogens or inflammatory stimuli.
  • Leukemia/Lymphoma: Significant abnormalities in WBC morphology or counts.
  • Clotting Disorders: Abnormal platelet counts (Thrombocytopenia or Thrombocytosis) can lead to excessive bleeding or inappropriate clot formation.

Panel Components

This test is a profile comprising the following specific markers:

Mean Corpuscular Hemoglobin (MCH)
pg
Mean Corpuscular Hemoglobin Concentration (MCHC)
g/dL
Mean Corpuscular Volume (MCV)
fL
Red Blood Cell Count
x10^6/µL
Hematocrit (Hct)
%
White Blood Cell Count (WBC)
10^3/µL
Mean Platelet Volume (MPV)
fL
Platelet Count (PLT)
x10^3/µL
Red Cell Distribution Width (RDW)
%
Hemoglobin (Hgb)
g/dL

Why Context Matters

Factors such as severe dehydration can falsely elevate hemoglobin and hematocrit concentrations (hemoconcentration). Conversely, overhydration can dilute the blood. Strenuous exercise, smoking, and high-altitude living also significantly shift normal baselines, necessitating a second look if the clinical picture doesn't match the lab results.

Lab ranges are statistical averages, not biological laws. "Normal" for a 20-year-old male isn't normal for a 60-year-old female.

Clinical References

Source-of-truth databases and clinical guidelines for Complete Blood Count (CBC):

Research & Guidelines

Related Indicators

Activated Partial Thromboplastin Time (APTT)

View Range

AML Comboquest 9

View Range

Blood Cell Morphology

View Range
DR

Medically Reviewed by Dr. Binoy Babu, MBBS

Board Certified Doctor • 10+ Years Clinical Experience

Dr. Babu is a practicing physician dedicated to empowering patients with clear, actionable medical information. He founded 2opi to bridge the gap between complex lab reports and patient understanding, ensuring everyone has access to a reliable second opinion.

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