Anemia

A n e m i a

Definition: Anemia is a reduction below normal in hemoglobin or red blood cell count.

Causes

Blood loss

Excessive red blood cell destruction

• Extracorpuscular hemolytic disease (autoimmune disorders, infection (e.g.,

malaria), hypersplenism, trauma to red blood cells)

• Intracorpuscular hemolytic disease (hereditary red cell membrane

or globin synthesis abnormalities)

Decreased red blood cell production

• Bad diet (not enough iron, vitamin B12, or folate)

• Decreased number of erythroblasts (as in aplastic anemia)

• Bone marrow full of things besides hematopoietic precursors (e.g., tumor)

• Chronic disease (e.g., renal disease, inflammatory disease)

• Cirrhosis

Morphologic Groups

Abnormal size

• Red cells too small (microcytic)

• Iron-deficiency anemia

• Anemia of chronic disease

• Thalassemia

• Red cells too big (macrocytic)

• Megaloblastic anemia

• Non-megaloblastic anemia

Abnormal shape

• Round red cells (spherocytes)

• Hereditary spherocytosis

• Autoimmune hemolytic anemia

• Elongated red cells

• Sickle cell anemia (sickles)

• Anemia associated with splenomegaly or myelophthisis (teardrops)

• Pointy red cells

• Glucose-6-phosphate dehydrogenase deficiency (bite cells)

• Microangiopathic hemolytic anemia (schistocytes)

Normal size and shape

• Increased reticulocytes

• Hemorrhage (onset >3 days ago)

• No increase in reticulocytes

• Hemorrhage (onset <3 days ago)

• Anemia of chronic disease

• Iron-deficiency anemia (early stages)

• Aplastic anemia

• Anemia of chronic renal disease

• Anemia due to bone marrow infiltration

Check your knowledge

When you finish studying the anemias you should be able to:

□ Understand the physiologic

causes of anemia

□ List the major types of anemia

and describe their clinical and

morphologic features.

□ Formulate a differential

diagnosis for anemia given a

clinical setting, an MCV, and a

few salient morphologic

features.