Megaloblastic anemia
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Megaloblastic anemia is anemia resulting from a deficiency of vitamin B12 and folic acid.
Causes
- nutritional defects (vitamin B12 is mainly from animal sources, and vegans may require supplementation)
- chronic liver diseases
- decreased production of intrinsic factor (this disease entity is called pernicious anemia)
- intestinal malabsorption (due to an enteritis, celiac disease or other causes).
- fish tapeworm infestation (Diphyllobothrium latum)
Hematological findings
The blood film can point towards vitamin deficiency:- Decreased red blood cell (RBC) count and hemoglobin levels
- Increased mean corpuscular volume (MCV, >100 fl) and mean corpuscular hemoglobin (MCH)
- The reticulocyte count is normal
- The platelet count may be reduced.
- Neutrophil granulocytes may show multisegmented nuclei ("senile neutophil"). This is thought to be due to decreased production and a compensatory prolonged lifespan for circulating neutrophils.
- Anisocytosis (increased variation in RBC size) and poikilocytosis (abnormally shaped RBCs).
- Macrocytes (larger than normal RBCs) are present.
- Ovalocytes (oval shaped RBCs) are present.
- Bone marrow (not normally checked in a patient suspected of megaloblastic anemia) shows megaloblastic hyperplasia.
Analysis
The Schilling test is often performed to determine the nature of the vitamin B12 deficiency.
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