Anemia (from Greek "an" meaning "not", and "heme" meaning "blood") is a decrease in the number/quality, of RBC/hemoglobin, thereby reducing the oxygen carrying ability of blood, and thus causing lack of oxygen in organs. Derived from Greek "an" meaning "not", and "emia" meaning "blood". It is the most common blood disorder.

• Hemorrhage, excessive blood volume loss:
  • Trauma
  • GI bleeding
• Hemolysis, excessive blood cell destruction:
  • Hemolytic anemia, which is a form of anemia due to hemolysis. Autoimmune hemolytic anemia (AIHA) is where antibodies are directed against a person's own RBC causing them to lyse, reducing their lifetime from the normal 110 days to just a few days. AIHA is Ix using Coombs test (aka antiglobulin test), which can either be direct antiglobulin test (DAT) or indirect antiglobulin test (IAT). DAT involves washing a Pt's RBC's using their own plasma, and then incubated with antihuman globulin, producing clumping of RBC's, a visual indication that autoantibodies are bound to the surface of RBC's
  • Sickle cell anemia
  • Infections, e.g. malaria
  • Some autoimmune diseases
• Reduced hematopoiesis, deficient RBC production:
  • Iron deficiency anemia
  • Lack of vitamin B12
  • Thalassemia
  • Numerous neoplasms of bone marrow

It can also be classified by size of RBC:

• Microcytic anemia
• Normocytic anemia
• Macrocytic anemia

• When the onset of anemia is slow, the Sx are often vague:
  • Feeling tired
  • Weakness
  • Shortness of breath
  • Poor ability to exercise
• When the onset of anemia is quick, the Sx are often greater:
  • Confusion
  • Syncope (feeling like passing out)
  • Increased thirst
• Pale, will only occur when the Pt has significant anemia

• Blood transfusion, is based on either presence of Sx, or Hg<6-8g/dL
• Erythropoiesis-stimulating medications are only recommended in those w/ severe anemia

• Prognosis depends on the cause of anemia, and its severity
• Young Pt's recover from anemia quicker than older Pt's

• Most common blood disorder, affecting 25% of persons globally
• More common in females than males, among children, during pregnancy, and in the elderly

• Hemoglobin
• Anemia of prematurity
• Iron deficiency anemia
• Microcytic anemia, Macrocytic anemia, Normocytic anemia
• Anemia of chronic disease