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Size of normal red cells 

7.5 micrometers(mm)in diameter

Characteristics of normal RBC

Central concavity and pallor

 Variation in size of RBC's is called Anisocytosis.

Anisocytosis is encountered in

  1. Megaloblastic anemia
  2. Iron deficiency anemia

Variation in shape. Abnormal shapes of red blood cells


  1. Megaloblastic anemia
  2. Iron deficiency anemia

 Microcytic and Hypochromic : Smaller than normal with prominent central pallor

    1. Iron deficiency anemia Causes include: Blood loss Pregnancy Impaired GI absorption
    2. Beta Thalessemia
    3. Sideroblastic anemia

Macrocytic : Larger than normal

  1. Chronic hepatic disorders, i.e. cirrhosis, chronic hepatitis
  2. Alcoholism
  3. Hypothyroidism
  4. Megaloblastic anemia (Vitamin B12 or folate deficiencies)
  5. Myelodysplasia


 Sickle Cells: Elongated crescentic red blood cells

  1. Sickle cell hemoglobinopathies (e.g.SS,SC, S-thalassemia)
  2. Rarely seen in sickle trait(AS)smear.


Elliptocytes: Cells are elliptical in shape.

  1. Hereditary elliptocytosis
  2. Thalassemia
  3. Iron Deficiency


Target Cells: Central and outer rim staining with intervening ring of pallor

  1. Liver disease
  2. Thalessemia
  3. Hemoglobin C disease
  4. Sickle cell disease


Acanthocytes: Also called Spur cells Irregularly spiculated . Dense center.

Due to altered cell membrane lipids

  1. Severe liver disease 
  2. Abetalipoproteinemia
  3. Rarely seen in anorexia nervosa
  4. Malabsorption
  5. Post Splenectomy


Polychromatophilia: Reticulocytes: Blue hue in macrocytes

  1. Hemolytic anemia
    • Thalassemia Major
    • Autoimmune Hemolysis
  2. Hemorrhage
  3. After replacement of Iron, B12, Folate


 Rouleaux Formation: Alignment of red blood cells in stacks (more than 4-5 per stack)

  1. Paraproteinemia as in multiple myeloma or macroglobulinemia
  2. High fibrinogen (inflammatory states; high ESR)
  3. Artifactual

 Howell jolly bodies : small basophilic dense inclusion

  1. Post Splenectomy
  2. Hemolytic anemia


Spherocytes :  Small hyperchromic cells lacking normal central pallor. 

  1. Hereditary spherocytosis
  2. Immune hemolytic anemia
  3. Post transfusion
  4. Glucose-6-phosphate dehydrogenase deficiency(Heinz body hemolytic anemias)