| RBC Trait
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Appearance
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Physiology
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Associated Conditions
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Follow-up Testing
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| Rouleaux
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Stacked formation ("stack of coins") in monolayer
- Often seen with blue background staining
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- Increased amount of plasma proteins
- Excess protein have + charge that reduces RBC membrane charge (zeta potential)
- Reduced charge allows cells to stack (due to biconcave shape)
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- Multiple myeloma/plasma cell myeloma
- Chronic liver disease
- Lymphomas
- Acute and chronic inflammatory diseases (especially when plasma proteins like fibrinogen or globulins are increased)
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Saline replacement to remove excess protein
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| Agglutination
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Irregular clumping of cells in monolayer
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- Caused by IgM antibodies (cold agglutinins)
- Large antibodies can span zeta potential gaps and form lattice with other antibody-coated cells
- IgMs bind to RBCs at room temperature
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- Cold autoimmune hemolytic anemia
- IgM-associated lymphomas
- Multiple myeloma
- Paroxysmal cold hemoglobinuria
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Pre-warm sample to 37C to dissociate cold IgMs
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| Microcytosis
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Smaller cells (round, biconcave)
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- More divisions causing smaller cells
- Hemoglobin errors - cells continue dividing to reach adequate hemoglobin concentrations
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- Thalassemia (small, uniform size - N RDW)
- IDA (small, varying size - ↑ RDW)
- Anemia of chronic inflammation
- Lead poisoning
- Hemoglobinopathies
- Sideroblastic anemia
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| Macrocytosis
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Round macrocytes (size)
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- Increases in cell membrane size (more cholesterol)
- Retain shape, but with larger membrane
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Moderate ↑ MCV
- Liver disease
- Normal neonate
- Reticulocytosis
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| Oval macrocytes (shape)
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- Fewer divisions causing larger cells - errors in DNA synthesis
- Cytoplasm increases, but DNA doesn't (asynchrony)
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Marked ↑ MCV
- Megaloblastic anemia (B12/folate deficiency)
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| Hypochromasia
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Cells >1/3 central pallor
- 1/2-2/3 moderate
- >3/4 marked
- Consistent field-to-field, gradual colour change
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- Decreased or abnormal hemoglobin
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- IDA
- Thalassemias
- Sideroblastic anemia
- Lead poisoning
- Some anemia of chronic inflammation
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↓ MCH, ↓ MCHC
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| Increased polychromasia
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Larger, irregular bluish cells, without central pallor
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- Cells at final stage of RBC maturation
- Have lost nucleus but have not assumed final biconcave shape
- Increase indicates bone marrow response to push out immature cells (compensatory mechanism)
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- 0.5-2.5% normal in adults
- Increased in conditions causing RBC damage or destruction
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Reticulocyte count
- Manual supravital staining (methylene blue to visualize RNA)
- Automated immature reticulocyte fraction (IRF) to stain nucleic acids
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Combinations
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| Dual Population
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Usually normal population with abnormal population
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- Condition being treated (newer, healthy population)
- Condition plus blood transfusion
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| Normocytic/normochromic
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Normal size and colour of RBC
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- Normal patient
- Anemia from reduced RBC numbers (hemorrhage, burns, etc.)
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| Hypochromic/microcytic
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Small cells with large central pallor
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- Anemia from abnormal hemoglobin production or metabolism (e.g., IDA)
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RBC Metabolism
RBC Breakdown
Extravascular Hemolysis (Macrophage-Mediated Hemolysis)
- Occurs in spleen, primarily due to splenic macrophages
- Slower movement through splenic sinusoids allows older or damaged cells to be destroyed
- RBC contents salvaged and metabolized
- Hemoglobin broken down into globin chains and iron
- Most (90%) of RBCs are destroyed this way
Intravascular Hemolysis (Fragmentation/Mechanical Hemolysis)
- Occurs inside blood vessels
- Mechanical damage to cells causing hemolysis
- Can also be caused by damage to blood vessels (e.g., clots)
- RBC contents also salvaged
- Hemoglobin binds to transport proteins (primarily haptoglobin when available, if hemoglobin oxidizes then binds to hemopexin)
- Taken to liver (hemoglobin) or excreted by kidney
- Less common (10-20%) method of RBC destruction
