Week 4: Macrocytic Anemia

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Week 4 Macrocytic Anemia

• Macrocytosis
• Vitamin B12
• Folic acid
• Megaloblastic changes
• Pernicious anemia
• Schilling test
• Hypersegmented PMN

• Bone marrow analysis
• WBC precursors
• Liver disease
• Polycythemia and erythremia
• PV
• Newborn CBC

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Bone Marrow Analysis

• Aspirate
• Particles in fluid part of marrow
• Differential count
• Biopsy
• Solid part of the marrow
• Cellularity
• Clot section

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Aspiration
Biopsy
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WBC Precursors

• Myeloblast
• Promyelocyte
• Primary azurophilic granules
• Meylocyte
• Specific granules
• Metamyelocyte
• Band, stab
• Segmented neutrophil, PMN

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Myeloblast
Promyelocyte
Neutrophilic Myelocyte
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Segmented neutrophil and lymphocyte
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Mast cell and histiocyte
Megakaryocyte
Plasma cell
Mast cell
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Histiocyte
Fat cell
Macrophage
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Osteoclasts
Giant cell
Osteoblasts
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Non-Megaloblastic Macrocytosis

• Alcoholism
• Poor nutrition
• Cirrhosis
• Liver disease
• Reticulocytosis
• Hemolytic anemia
• Hemorrhage

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Megaloblastic Anemia

• Hemolytic changes
• Waxy pallor
• Neurologic changes with B12 deficiency
• Glossitis, beefy red or smooth pale tongue

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Causes of Megaloblastic Anemia

• Folate deficiency
• Dietary (green leafy vegetables)
• Malabsorption
• B12 deficiency
• Dietary
• Fish tapeworm (D latum)
• Pernicious anemia
• Lack of gastric intrinsic factor (IF) for
  absorption

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B12 Metabolism

• Bind to cobalophilin (cobalamine binding protein)
  in saliva and gastric secretion
• Bind to IF (from parietal cell) in the duodenum
• Cbl-IF complex bind to receptor (cubilin) at
  distal ileum for mucosal absorption
• 1 B12 can be absorbed without IF (megadose of
  B12 for IF deficiency, no need for IV)

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Autoimmune mechanism for PA
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Megaloblastic Lab Changes

• MCV up to 140 fL
• Howell-Jolly bodies and Cabot rings
• Hypersegmented PMN
• Pancytopenia
• BM with low ME ratio

• Megaloblastic morphology (giant bands and metas)
• B12 and folate assays
• RBC folate (long term indicator)
• IF antibody (PA)
• Schilling test (obsolete)

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Hypersegmented PMN
Megaloblastic anemia
Megaloblastic BM
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Other Apparent Macrocytoses

• Cold agglutinin
• Prewarm samples
• Hyperglycemia
• Osmotic changes
• Clot
• Rouleaux

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Polycythemia Vera

• A type of myeloproliferative disorder (MPD)
• Independent of EPO
• High total RBC mass (by radio tagging)

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Secondary Polycythemia

• Dehydration (decreased plasma volume)
• Increased O2 demand (e.g., emphysema, high
  elevation)
• High EPO (e.g., kidney tumor)