Medical Importance
Megaloblastic anemias are characterized by morphologic changes
resulting from pathologic impairment of DNA synthesis. Most often,
these anemias result from deficiencies of folate and/or vitamin B12.
When evaluating a patient with megaloblastic anemia, it is crucial to
determine which of these vitamins is actually deficient and to define
the disease state responsible for the deficiency.
Objectives
- List the causes of macrocytic anemia.
- Describe the morphologic hallmarks of megaloblastic erythropoiesis and granulopoiesis in the blood and bone marrow.
- Diagram
the biochemical pathway which explains how folate and vitamin B12
deficiency ultimately impair thymidylate synthesis, and methionine and
fatty acid metabolism.
- Identify the dietary sources of
vitamin B12 and folate and to describe their associated sites and
mechanisms of absorption, means of transport, and duration and location
of storage.
- Describe the differences between vitamin B12 deficiency and folate deficiency with respect to:
- their most common causes
- time to development of the clinical deficiency state
- presence of neurologic and neuropsychiatric abnormalities
- Describe the clinical, laboratory and autoimmune findings associated with pernicious anemia.
- List the appropriate therapies for B12 deficiency and folate deficiency.
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