Anemia

A deficiency in
- Number of erythrocytes (RBCs)
- Quantity of hemoglobin
- Volume of packed RBCs (hematocrit)
RBC function
- Transport oxygen (O2) from lungs to systemic tissues
- Carry carbon dioxide from tissues to lungs
Not a specific disease
Manifestation of a pathologic process
Diagnosed based on
- Complete blood count (CBC)
- Reticulocyte count
- Peripheral blood smear

Cause of anemia

Decreased RBC production
- Deficient nutrients
  - Iron
  - Cobalamin
  - Folic acid
- Decreased erythropoietin
- Decreased iron availability
Blood loss
- Chronic
  - Bleeding duodenal ulcer
  - Colorectal cancer
  - Liver disease
- Acute
  - Acute trauma
  - Ruptured aortic aneurysm
  - GI bleeding
Increased RBC destruction
- Hemolysis
  - Abnormal hemoglobin (Sickle cell disease)
  - Medication (e.g., methyldopa [Aldomet]) and chemicals (e.g., chemotherapy, lead)
  - Incompatible blood
    - Antibodies against RBCs
  - Physical destruction
    - Prosthetic heart valves
    - Extracorporeal circulation
    - Disseminated intravascular coagulopathy (DIC)
    - Thrombotic thrombocytopenic purpura (TTP)
  - Trauma (e.g., cardiopulmonary bypass)
  - Infectious agents (e.g., malaria) and toxins
  - Radiation

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