Introduction to Hematology
You should know a little bit about how to approach a patient with a suspected hematologic disorder. These general tips will help you build a framework for the in-depth discussions of specific diseases we will cover later...and they will help you as you begin to take care of patients in your third and fourth years of medical school.
What are some of the tip-offs that your patient may have a hematologic disorder? How should you direct your physical exam if you are concerned about a hematologic disorder?
What are the components of the complete blood count (CBC)? In plain English, what does each measure? Which components are most useful,
and why?
Look at the red blood cells
• Estimate number.
• Look for variation in size (anisocytosis).
• Oval macrocytes (B /folate deficiency)
• Microcytes (iron deficiency anemia, thalassemia)
• The size range can often help you narrow down which type of anemia is
present!
• Look for variation in shape (poikilocytosis).
• Schistocytes (microangiopathic hemolytic anemia)
• Spherocytes (hemolytic anemia, hereditary spherocytosis)
• Teardrop cells or dacryocytes (myelofibrosis or myelophthisic processes)
• Target cells or codocytes (hemoglobinopathies, thalassemias, liver
disease, the post-splenectomy state)
• Sickle cells (sickle cell anemia)
• Echinocytes and acanthocytes (liver disease)
• Estimate the average amount of hemoglobin in each cell (chromasia).
• Normochromic – Zone of central pallor comprises about 1/3 of the cell
diameter.
• Hypochromic – Zone of central pallor comprises >1/3 of the cell diameter.
• The lower the Hgb, the higher the reticulocyte count should be.
• Look for anything else weird.
• Nucleated red blood cells
• Inclusions (Howell-Jolly bodies, Pappenheimer bodies, bugs)
Look at the platelets
• Estimate number.
• Check morphology (size, granulation).
Look at the white blood cells
• Estimate number.
• Check morphology.
• Do a differential count.
