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Hematology > Week 1 > Flashcards

Week 1 Flashcards

Introduction to Hemolytic Anemia, Intrinsic & Extrinsic Immune Defects Leading to HA

1
Q

What is hemolytic anemia, and what causes it?

A

Hemolytic anemia occurs when the rate of red blood cell (RBC) destruction exceeds the rate of RBC production by the bone marrow. This imbalance leads to a decrease in RBCs, causing anemia.

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2
Q

How are hemolytic anemias classified?

A

Acute vs Chronic
Inherited vs Acquired
Intrinsic vs Extrinsic
Intravascular vs Extravascular

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3
Q

Which inherited hemolytic anemias are caused by membrane defects?

A

Hereditary Spherocytosis
Hereditary Elliptocytosis
Hereditary Stomatocytosis

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4
Q

What are examples of enzyme defects in inherited hemolytic anemias?

A

G6PD Deficiency
Pyruvate Kinase Deficiency

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5
Q

What disorders involve globin structure and synthesis in inherited hemolytic anemias?

A

Hemoglobinopathies
Thalassemias

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6
Q

What are the two main categories of acquired hemolytic anemia?

A

Immune
Non-Immune

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7
Q

What are the immune causes of acquired hemolytic anemia?

A

Alloimmune:
Transfusion reactions
Hemolytic disease of the newborn

Autoimmune:
Warm antibody
Cold antibody

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8
Q

What are the non-immune causes of acquired hemolytic anemia?

A

Chemical & physical agents
Infections
Mechanical factors
Secondary liver & renal disease

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9
Q

What percentage of hemolysis is normally carried out via extravascular hemolysis?

A

90% of hemolysis is normally carried out through extravascular hemolysis.

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10
Q

What happens to hemoglobin during extravascular hemolysis?

A

Hemoglobin is broken down by macrophages into:

Heme (or metheme), which is further processed to release iron
Unconjugated bilirubin

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11
Q

What role does the liver play in extravascular hemolysis?

A

The liver converts unconjugated bilirubin into conjugated bilirubin, which is excreted into the intestine as part of bile.

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12
Q

What happens to urobilinogen during extravascular hemolysis?

A

Some urobilinogen is reabsorbed into circulation, with the remainder excreted as:

Urine urobilinogen (normal levels)
Fecal urobilinogen (normal levels)

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13
Q

How does the kidney participate in the clearance of bilirubin in normal extravascular hemolysis?

A

The kidney excretes normal levels of urine urobilinogen, and no urine bilirubin is present (negative).

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14
Q

What percentage of hemolysis is carried out via intravascular hemolysis?

A

Approximately 10% of hemolysis is carried out through intravascular hemolysis.

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15
Q

What is the role of haptoglobin (Hpt) in intravascular hemolysis?

A

Haptoglobin binds to free hemoglobin (Hb) released into circulation during intravascular hemolysis, forming an Hb-Hpt complex. This complex is then recognized by CD163 on macrophages for degradation.

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16
Q

What happens to hemoglobin during intravascular hemolysis once it is processed by macrophages?

A

Hemoglobin is degraded by macrophages, with the heme component processed into iron and unconjugated bilirubin, which is sent to the liver.

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17
Q

What happens to excess hemoglobin that is not bound by haptoglobin in intravascular hemolysis?

A

Excess hemoglobin that is not bound by haptoglobin can be bound by hemopexin (Hpx), which is recognized by CD91 receptors on hepatocytes for degradation.

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18
Q

How is unconjugated bilirubin processed during intravascular hemolysis?

A

Unconjugated bilirubin is transported to the liver, where it is converted into conjugated bilirubin and excreted into the intestine.

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19
Q

What is excessive extravascular hemolysis?

A

Excessive extravascular hemolysis occurs when red blood cells are destroyed at a faster rate than normal, leading to an increase in unconjugated bilirubin levels and overproduction of urobilinogen.

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20
Q

What happens to unconjugated bilirubin during excessive extravascular hemolysis?

A

Unconjugated bilirubin is produced in excess by macrophages and transported to the liver, where it is converted to conjugated bilirubin.

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21
Q

How does the liver handle the increased amount of unconjugated bilirubin in excessive extravascular hemolysis?

A

The liver processes the increased unconjugated bilirubin into conjugated bilirubin, which is then excreted into the intestines.

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22
Q

What happens to urobilinogen levels during excessive extravascular hemolysis?

A

Urobilinogen levels increase in both urine and feces, reflecting the higher turnover of red blood cells and bilirubin.

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23
Q

What would urine and fecal tests show in excessive extravascular hemolysis?

A

Urine: Increased urobilinogen, no bilirubin
Feces: Increased urobilinogen

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24
Q

What occurs during excessive intravascular hemolysis?

A

Excessive intravascular hemolysis involves the destruction of red blood cells within the blood vessels, leading to increased levels of free hemoglobin and its binding to haptoglobin (Hpt) or hemopexin (Hpx).

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25
Q

What role does haptoglobin (Hpt) play in excessive intravascular hemolysis?

A

Haptoglobin binds free hemoglobin released into circulation. The Hb-Hpt complex is taken up by CD163 receptors on macrophages for degradation.

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26
Q

What happens if haptoglobin is depleted during excessive intravascular hemolysis?

A

If haptoglobin is depleted, excess free hemoglobin binds to hemopexin (Hpx), which is recognized by CD91 receptors on hepatocytes for degradation.

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27
Q

What is the fate of unconjugated bilirubin during excessive intravascular hemolysis?

A

Unconjugated bilirubin, produced from the breakdown of hemoglobin, is transported to the liver where it is converted into conjugated bilirubin and excreted into the intestine.

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28
Q

What are the changes in urine and fecal findings in excessive intravascular hemolysis?

A

Urine: Increased urobilinogen, no bilirubin
Feces: Increased urobilinogen

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29
Q

What are schistocytes, and what is their significance in excessive intravascular hemolysis?

A

Schistocytes are fragmented red blood cells often seen in excessive intravascular hemolysis, indicating red blood cell destruction within the blood vessels.

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30
Q

What happens to hemoglobin in the kidneys during excessive intravascular hemolysis?

A

Hemoglobin (Hb) is filtered by the kidneys, and some of it forms complexes with haptoglobin (Hb-Hpt) and is reabsorbed by proximal tubular cells. Excess free hemoglobin that is not bound can lead to hemoglobinuria.

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31
Q

What is hemoglobinuria, and when does it occur?

A

Hemoglobinuria is the presence of hemoglobin in the urine, occurring when free hemoglobin exceeds the capacity of haptoglobin and the renal tubules are unable to fully reabsorb it.

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32
Q

What is the role of proximal tubular cells in iron processing during excessive intravascular hemolysis?

A

Proximal tubular cells reabsorb hemoglobin and break it down into iron (Fe), which is stored as ferritin or hemosiderin. Some iron is released back into circulation via ferroportin.

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33
Q

What happens to unconjugated bilirubin in excessive intravascular hemolysis?

A

Unconjugated bilirubin is transported to the liver, where it is converted into conjugated bilirubin and excreted in bile. Excess bilirubin leads to increased levels of urobilinogen in both urine and feces.

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34
Q

How does iron get released from proximal tubular cells back into circulation?

A

Iron is released from proximal tubular cells into circulation via ferroportin, where it binds to transferrin for transport.

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35
Q

What are the common findings in the urine during excessive intravascular hemolysis?

A

Increased urine urobilinogen
Hemoglobinuria (if excess hemoglobin is filtered)
Negative urine bilirubin

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36
Q

What happens to plasma hemoglobin levels during an intravascular hemolytic event?

A

Plasma hemoglobin levels rise sharply immediately after the hemolytic event and then decline over the next few days as the free hemoglobin is processed or excreted.

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37
Q

How does serum haptoglobin behave during intravascular hemolysis?

A

Serum haptoglobin levels decrease rapidly after a hemolytic event as haptoglobin binds to free hemoglobin. It remains low during ongoing hemolysis.

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38
Q

What is the pattern of urinary hemoglobin following a hemolytic event?

A

Urinary hemoglobin peaks within the first 1-2 days following the hemolytic event and then decreases as free hemoglobin is processed or reabsorbed.

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39
Q

How do reticulocyte levels change after a hemolytic event?

A

Reticulocyte levels begin to rise a few days after the hemolytic event, indicating an increased response from the bone marrow to replace lost red blood cells.

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40
Q

What happens to plasma bilirubin levels during intravascular hemolysis?

A

Plasma bilirubin levels increase gradually following a hemolytic event due to the breakdown of hemoglobin into unconjugated bilirubin, which is processed by the liver.

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41
Q

What happens to serum haptoglobin levels during extravascular hemolysis?

A

Serum haptoglobin levels remain relatively stable during extravascular hemolysis, as haptoglobin is not consumed as quickly as in intravascular hemolysis.

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42
Q

How do plasma bilirubin levels change after a hemolytic event in extravascular hemolysis?

A

Plasma bilirubin levels increase gradually after the hemolytic event, peaking around day 3-4, due to the breakdown of hemoglobin into unconjugated bilirubin.

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43
Q

What is the trend in reticulocyte levels during extravascular hemolysis?

A

Reticulocyte levels increase over time following a hemolytic event, reflecting the bone marrow’s response to replace lost red blood cells, typically peaking around day 6-7.

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44
Q

What happens to whole blood hemoglobin levels in extravascular hemolysis?

A

Whole blood hemoglobin levels decrease after the hemolytic event as red blood cells are destroyed and hemoglobin is released.

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45
Q

How do plasma bilirubin and reticulocyte levels differ in their time course during extravascular hemolysis?

A

Plasma bilirubin peaks earlier, around day 3-4, while reticulocyte levels peak later, around day 6-7, indicating the delayed response of red blood cell production compared to hemoglobin breakdown.

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46
Q

What is the hemoglobin level, indirect bilirubinemia, and reticulocytosis pattern in acute fragmentation hemolytic anemia?

A

Hemoglobin: Rapidly dropping
Indirect bilirubinemia: Delayed
Reticulocytosis: Delayed
Schistocytes present

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47
Q

What are the characteristics of acute macrophage-mediated hemolytic anemia?

A

Hemoglobin: Rapidly dropping
Indirect bilirubinemia: Delayed
Reticulocytosis: Delayed
Spherocytes present

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48
Q

How does chronic fragmentation hemolytic anemia present?

A

Hemoglobin: Persistently low
Indirect bilirubinemia: Persistent
Reticulocytosis: Persistent
Schistocytes present

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49
Q

What is the presentation of chronic macrophage-mediated hemolytic anemia?

A

Hemoglobin: Persistently low
Indirect bilirubinemia: Persistent
Reticulocytosis: Persistent
Spherocytes present

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50
Q

How does acute hemorrhage differ from hemolytic anemia in terms of indirect bilirubinemia and reticulocytosis?

A

Hemoglobin: Rapidly dropping
Indirect bilirubinemia: Absent
Reticulocytosis: Delayed
No spherocytes or schistocytes

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51
Q

What are the findings in hemodilution?

A

Hemoglobin: Rapidly dropping
Indirect bilirubinemia: Absent
Reticulocytosis: Absent
No spherocytes or schistocytes

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52
Q

How does recovery from hemorrhage present in terms of reticulocytosis?

A

Hemoglobin: Rising
Indirect bilirubinemia: Absent
Reticulocytosis: Present
No spherocytes or schistocytes

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53
Q

What is the pattern in treated anemia (iron, vitamin B12, folate deficiency)?

A

Hemoglobin: Rising
Indirect bilirubinemia: Absent or declining
Reticulocytosis: Present
No spherocytes or schistocytes

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54
Q

What are the characteristics of hemorrhage into a body cavity?

A

Hemoglobin: Rapidly dropping
Indirect bilirubinemia: Delayed
Reticulocytosis: Delayed
No spherocytes or schistocytes

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55
Q

What is the presentation in ineffective erythropoiesis (e.g., megaloblastic anemia)?

A

Hemoglobin: Dropping
Indirect bilirubinemia: Persistent
Reticulocytosis: Absent
No spherocytes or schistocytes

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56
Q

What is the expected change in WBC and platelet counts (WBC/PLT) in hemolysis?

A

The WBC and platelet counts are variable in hemolysis.

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57
Q

What happens to RBC, hemoglobin (HB), and hematocrit (HCT) levels in hemolysis?

A

RBC, hemoglobin (HB), and hematocrit (HCT) levels are decreased in hemolysis.

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58
Q

What is the expected change in mean corpuscular volume (MCV) in hemolysis?

A

MCV is increased, although it may not be greater than the reference interval but will be higher than baseline.

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59
Q

What happens to red cell distribution width (RDW) in hemolysis?

A

RDW is increased in hemolysis.

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60
Q

What happens to reticulocyte levels in hemolysis?

A

Reticulocyte levels are increased in hemolysis, indicating an increased response from the bone marrow.

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61
Q

What hemolytic disorders are associated with the presence of spherocytes?

A

Hereditary spherocytosis
Warm hemolytic anemia
Thermal injury to RBCs

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62
Q

Which hemolytic disorder is associated with elliptocytes (ovalocytes)?

A

Hereditary elliptocytosis

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63
Q

What hemolytic disorders are associated with the presence of acanthocytes?

A

Abetalipoproteinemia
Severe liver disease

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64
Q

What conditions are associated with burr cells in hemolytic anemia?

A

Pyruvate kinase deficiency
Uremia

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65
Q

What disorder is linked with the presence of schistocytes?

A

Microangiopathic hemolytic anemia

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66
Q

What does erythrophagocytosis indicate in hemolytic anemia?

A

Erythrophagocytosis is linked to damage to the RBC surface, especially due to complement-fixing antibodies.

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67
Q

What disorders are associated with RBC agglutination in hemolytic anemia?

A

Cold agglutinins
Immunohemolytic disease

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68
Q

What are intrinsic hemolytic anemias?

A

Intrinsic hemolytic anemias are a group of disorders characterized by defects in red blood cells (RBCs) that result in hemolysis and anemia.

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69
Q

What are the three main categories of intrinsic hemolytic anemias?

A

Intrinsic hemolytic anemias can be divided into:

RBC membrane defects
Metabolic enzyme deficiencies
Hemoglobin abnormalities

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70
Q

What proteins are involved in the vertical and horizontal interactions of the RBC membrane?

A

The proteins include:

Ankyrin complex
Actin complex
Protein 4.2
α & β Spectrin
G3PD (band 6)

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71
Q

What is the primary function of the red blood cell (RBC) membrane?

A

The function of the RBC membrane is to provide deformability, elasticity, and stability to the cell.

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72
Q

What can result from defects in the red blood cell membrane?

A

A defect that changes membrane geometry, elasticity, or viscosity of the cytoplasm can affect deformability and lead to hemolysis.

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73
Q

Which complex is responsible for linking the RBC membrane to the cytoskeleton?

A

The ankyrin complex is responsible for linking the RBC membrane to the cytoskeleton, which is essential for maintaining cell stability and shape.

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74
Q

How do defects in the spectrin-ankyrin interaction impact RBCs?

A

Defects in the spectrin-ankyrin interaction can compromise the cell’s deformability, leading to fragility and increased susceptibility to hemolysis.

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75
Q

What are the classifications of major hereditary membrane defects causing hemolytic anemia?

A

Hereditary membrane defects causing hemolytic anemia are classified into:

Mutations that alter membrane structure
Mutations that alter membrane transport proteins

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76
Q

What are the hereditary membrane defects that alter membrane structure?

A

Hereditary spherocytosis
Hereditary elliptocytosis/pyropoikilocytosis

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77
Q

What hereditary membrane defect alters membrane transport proteins?

A

Hereditary stomatocytosis

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78
Q

Which hereditary conditions are associated with changes in the RBC membrane structure leading to hemolytic anemia?

A

Hereditary spherocytosis
Hereditary elliptocytosis
Pyropoikilocytosis

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79
Q

What is the inheritance pattern of hereditary spherocytosis?

A

75% autosomal dominant
25% nondominant

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80
Q

What proteins are deficient in hereditary spherocytosis?

A

The deficient proteins include:

Ankyrin (ANK1)
Band 3 (SLC4A1)
α-Spectrin (SPTA1)
β-Spectrin (SPTB)
Protein 4.2 (EPB42)

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81
Q

What is the pathophysiology of hereditary spherocytosis?

A

Hereditary spherocytosis involves a mutation in proteins that disrupts vertical membrane interactions between transmembrane proteins and the underlying cytoskeleton, leading to the loss of membrane and decreased surface area-to-volume ratio.

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82
Q

What is the typical red blood cell (RBC) morphology seen in hereditary spherocytosis?

A

Spherocytes
Polychromasia

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83
Q

What are the typical clinical features of hereditary spherocytosis?

A

The clinical presentation varies from asymptomatic to severe. Typical features include:

Splenomegaly
Jaundice
Anemia

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84
Q

What causes hereditary spherocytosis?

A

Hereditary spherocytosis is caused by deficiencies in proteins such as spectrin, ankyrin, or band 3, leading to defects in the red blood cell membrane structure.

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85
Q

What are the intrinsic abnormalities in hereditary spherocytosis?

A

Deficiency of spectrin, ankyrin, or band 3
Uncoupling of the lipid bilayer and skeleton
Microvesicle formation leading to membrane loss
Surface area deficiency resulting in spherocytosis

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86
Q

What happens to the red blood cell (RBC) membrane in hereditary spherocytosis?

A

The RBC membrane undergoes microvesicle formation, which leads to a loss of membrane surface area and results in the characteristic spherical shape of RBCs (spherocytosis).

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87
Q

What are the complete blood count (CBC) findings in hereditary spherocytosis?

A

Decreased hemoglobin
Increased mean cell hemoglobin concentration (MCHC)
Increased red cell distribution width (RDW)
Increased reticulocyte count
Hyperchromic (hyperdense) RBCs

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88
Q

What is the result of the direct antiglobulin test (DAT) in hereditary spherocytosis?

A

The direct antiglobulin test is negative in hereditary spherocytosis.

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89
Q

What are the indicators of hemolysis in hereditary spherocytosis?

A

Decreased serum haptoglobin
Increased serum lactate dehydrogenase (LDH)
Increased serum indirect bilirubin

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90
Q

What are additional tests for atypical cases of hereditary spherocytosis?

A

Decreased fluorescence in eosin-5’-maleimide binding test by flow cytometry
Increased osmotic fragility and incubated osmotic fragility tests
SDS-PAGE analysis of membrane proteins

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91
Q

What is the inheritance pattern of hereditary elliptocytosis?

A

Hereditary elliptocytosis follows an autosomal dominant inheritance pattern.

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92
Q

What proteins are deficient in hereditary elliptocytosis?

A

The deficient proteins include:

α-Spectrin (SPTA1)
β-Spectrin (SPTB)
Protein 4.1 (EPB41)

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93
Q

What is the pathophysiology of hereditary elliptocytosis?

A

Hereditary elliptocytosis is caused by a mutation in proteins that disrupts the horizontal linkages in the cytoskeleton, leading to a loss of mechanical stability in the red blood cell membrane.

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94
Q

What is the typical RBC morphology seen in hereditary elliptocytosis?

A

Few to 100% elliptocytes
Schistocytes in severe cases

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95
Q

What are the clinical findings in hereditary elliptocytosis?

A

90% of cases are asymptomatic
10% of cases show moderate to severe anemia

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96
Q

What is the inheritance pattern of hereditary pyropoikilocytosis?

A

Hereditary pyropoikilocytosis follows an autosomal recessive inheritance pattern.

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97
Q

What proteins are deficient in hereditary pyropoikilocytosis?

A

The deficient proteins include:

α-Spectrin (SPTA1)
β-Spectrin (SPTB)
Mutations are often homozygous or compound heterozygous

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98
Q

What is the pathophysiology of hereditary pyropoikilocytosis?

A

Hereditary pyropoikilocytosis is caused by a mutation in spectrin that disrupts horizontal linkages in the cytoskeleton, leading to severe red blood cell (RBC) fragmentation.

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99
Q

What is the typical RBC morphology seen in hereditary pyropoikilocytosis?

A

Elliptocytes
Schistocytes
Microspherocytes

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100
Q

What are the clinical findings in hereditary pyropoikilocytosis?

A

Severe anemia is a common clinical finding in hereditary pyropoikilocytosis.

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101
Q

What is the inheritance pattern of hereditary stomatocytosis?

A

Both overhydrated and dehydrated hereditary stomatocytosis follow an autosomal dominant inheritance pattern.

102
Q

What are the deficient proteins in overhydrated hereditary stomatocytosis?

A

Rh-associated glycoprotein (RHAG)
Others are unknown

103
Q

What are the deficient proteins in dehydrated hereditary stomatocytosis?

A

Piezo-type mechanosensitive ion channel component 1 (PIEZO1)
Potassium calcium-activated channel subfamily N member 4 (KCNN4)

104
Q

What is the pathophysiology of overhydrated hereditary stomatocytosis?

A

A mutation in a protein increases membrane permeability to sodium and potassium. High intracellular sodium causes an influx of water, leading to increased cell volume (↑ MCV) and decreased cytoplasmic viscosity (↓ MCHC).

105
Q

What is the pathophysiology of dehydrated hereditary stomatocytosis?

A

A mutation in a protein increases membrane permeability to potassium, causing low intracellular potassium and water loss from the cell. This leads to decreased cell volume (↓ MCV) and increased cytoplasmic viscosity (↑ MCHC).

106
Q

What is the typical red blood cell (RBC) morphology in overhydrated hereditary stomatocytosis?

A

Stomatocytes (5%–50%)
Macrocytes

107
Q

What is the typical red blood cell (RBC) morphology in dehydrated hereditary stomatocytosis?

A

Target cells
Burr cells
Stomatocytes (<10%)
RBCs with “puddled” hemoglobin at the periphery
Desiccated cells with spicules

108
Q

What are the clinical findings in overhydrated hereditary stomatocytosis?

A

Moderate to severe hemolytic anemia.

109
Q

What are the clinical findings in dehydrated hereditary stomatocytosis?

A

Mild to moderate anemia, splenomegaly.

110
Q

What is Rh Deficiency Syndrome?

A

Rh Deficiency Syndrome is a rare hereditary condition in which the expression of Rh membrane proteins on red blood cells (RBCs) is absent, leading to mild to moderate hemolytic anemia (HA).

111
Q

What red blood cell (RBC) morphology is seen in Rh Deficiency Syndrome?

A

Stomatocytes and occasional spherocytes can be seen on peripheral blood smears (PBS).

112
Q

What is the treatment for Rh Deficiency Syndrome?

A

The treatment for Rh Deficiency Syndrome is splenectomy.

113
Q

What is acquired stomatocytosis?

A

Acquired stomatocytosis is often a drying artifact on Wright-stained peripheral blood films. It has also been associated with acute alcoholism and certain medications.

114
Q

What conditions have been associated with acquired stomatocytosis?

A

Acute alcoholism and certain medications have been associated with acquired stomatocytosis.

115
Q

What metabolic process do red blood cells (RBCs) rely on for their metabolic needs?

A

Red blood cells rely on anaerobic glycolysis for their metabolic needs.

116
Q

What are the two most important metabolic pathways for RBCs?

A

The two most important metabolic pathways for RBCs are:

Embden-Meyerhof pathway
Hexose monophosphate shunt

117
Q

What are two key enzymes in the RBC metabolic pathways?

A

Glucose-6-phosphate dehydrogenase (G6PD)
Pyruvate kinase (PK)

118
Q

What are the two most common enzymopathies encountered in RBCs?

A

The most common enzymopathies are deficiencies in:

Glucose-6-phosphate dehydrogenase (G6PD)
Pyruvate kinase (PK)

119
Q

How do deficiencies in G6PD and PK affect red blood cells?

A

Deficiencies in G6PD and PK decrease the life span of red blood cells, leading to hemolytic anemia (HA).

120
Q

What is the role of G6PD in red blood cells?

A

G6PD is needed to protect hemoglobin, proteins, and lipids from oxidative denaturation in red blood cells.

121
Q

What reaction does G6PD catalyze in red blood cells?

A

G6PD catalyzes the first step in a series of reactions that detoxify hydrogen peroxide formed from oxygen radicals.

122
Q

How do red blood cells with normal G6PD activity respond to oxidative stress?

A

RBCs with normal G6PD activity can prevent cellular damage and safeguard hemoglobin from hydrogen peroxide during oxidative stress.

123
Q

What is the significance of NADPH in the G6PD pathway?

A

G6PD is the only means of generating NADPH, which is required for the detoxification of hydrogen peroxide during oxidative stress.

124
Q

How does G6PD deficiency affect the detoxification process in red blood cells?

A

In G6PD deficiency, red blood cells cannot produce enough NADPH to detoxify hydrogen peroxide, leading to oxidative damage and hemolysis.

125
Q

What is the inheritance pattern of G6PD deficiency?

A

G6PD deficiency is inherited in an X-linked pattern.

126
Q

How many genetic variants of G6PD deficiency have been identified?

A

Over 400 genetic variants of G6PD deficiency have been identified.

127
Q

How are the variants of G6PD deficiency classified?

A

The variants of G6PD deficiency are classified into five classes, with Class V being mild and Class I being chronic and severe.

128
Q

What is the global prevalence of G6PD deficiency related to?

A

The global prevalence of G6PD deficiency is higher in geographic areas where malaria is endemic.

129
Q

Which factors are associated with areas affected by G6PD deficiency and malaria?

A

Areas affected by G6PD deficiency are often associated with:

Malaria
Fava bean consumption
Regions where both G6PD deficiency and malaria overlap

130
Q

Why can’t G6PD deficient red blood cells (RBCs) effectively detoxify hydrogen peroxide (H₂O₂)?

A

G6PD deficient RBCs cannot make enough NADPH to effectively detoxify hydrogen peroxide (H₂O₂) during oxidative stress.

131
Q

What happens to hemoglobin during oxidative stress in G6PD deficiency?

A

Oxidation converts hemoglobin to methemoglobin and forms additional bonds, making it less soluble. This results in the formation of precipitates called Heinz bodies.

132
Q

What are Heinz bodies, and how do they affect RBCs?

A

Heinz bodies are precipitates of hemoglobin that adhere to the inner membrane of RBCs, causing irreversible damage.

133
Q

What happens to RBCs with Heinz bodies in G6PD deficiency?

A

RBCs with Heinz bodies are rapidly removed from circulation, primarily through intravascular hemolysis. Some extravascular hemolysis may occur in milder cases.

134
Q

What is the consequence of G6PD deficiency during oxidative stress?

A

The inability to detoxify H₂O₂ leads to oxidative damage of hemoglobin, formation of Heinz bodies, and premature destruction of RBCs through hemolysis.

135
Q

What is drug-induced hemolytic anemia (HA) in G6PD deficiency?

A

Drug-induced hemolytic anemia occurs when oxidative stress caused by drugs like malarial or sulfa drugs triggers a hemolytic crisis in individuals with G6PD deficiency.

136
Q

What is the most common cause of hemolysis in G6PD deficiency?

A

Infection-induced hemolytic anemia is the most common cause of hemolysis, thought to be linked to the generation of H₂O₂ by phagocytizing white blood cells (WBCs).

137
Q

What is favism in the context of G6PD deficiency?

A

Favism is a rare but severe hemolytic episode that occurs after the ingestion of fava beans in individuals with G6PD deficiency.

138
Q

What is neonatal hyperbilirubinemia in G6PD deficiency?

A

Neonatal hyperbilirubinemia is associated with G6PD deficiency and presents as jaundice 2-3 days after birth, not typically associated with anemia.

139
Q

What is chronic hereditary nonspherocytic hemolytic anemia (HA) in G6PD deficiency?

A

A small percentage of individuals with G6PD deficiency can develop a chronic form of hemolysis known as chronic hereditary nonspherocytic hemolytic anemia, characterized by ongoing hemolysis that is more extravascular than intravascular.

140
Q

What are the complete blood count (CBC) findings in G6PD deficiency during a hemolytic episode?

A

White blood cell (WBC) count: moderately elevated
Platelet (PLT) count: variable
Hemoglobin: decreased
Reticulocyte count: increased

141
Q

What biochemistry findings are seen during a hemolytic episode in G6PD deficiency?

A

Serum haptoglobin: severely decreased
Hemoglobinemia: present
Hemoglobinuria: present

142
Q

What peripheral blood smear (PBS) findings are associated with G6PD deficiency during a hemolytic episode?

A

Anisocytosis
Poikilocytosis
Spherocytosis
Schistocytosis
Bite cells and blister cells
(Severity of these findings can vary)

143
Q

What confirmatory tests are used for diagnosing G6PD deficiency during a hemolytic episode?

A

Supravital staining: Heinz bodies are seen
G6PD activity assay: decreased activity
Genetic testing: detects mutations in the G6PD gene

144
Q

What happens to hemoglobin levels during a hemolytic episode in G6PD deficiency?

A

Hemoglobin levels are decreased during a hemolytic episode.

145
Q

What are bite and blister cells?

A

Bite and blister cells are red blood cells (RBCs) where aggregated hemoglobin pulls away from the RBC membrane, leaving a clear area. If parts of the membrane are still visible, they are called blister cells.

146
Q

In which condition are bite and blister cells commonly seen?

A

Bite and blister cells are commonly seen in conditions like G6PD deficiency, where hemolysis occurs due to oxidative stress.

147
Q

Why are most hemolytic episodes in G6PD deficiency self-limiting?

A

Most hemolytic episodes are self-limiting because newly formed reticulocytes have higher levels of G6PD activity than mature RBCs, which helps compensate for the deficiency.

148
Q

What is the first step in treating a hemolytic episode in G6PD deficiency?

A

The first step is to discontinue the oxidative agent, which may involve stopping a drug or treating an underlying infection.

149
Q

When is transfusion necessary in G6PD deficiency?

A

Transfusion may be necessary in severe cases of hemolysis where there is significant anemia.

150
Q

What are key prevention strategies for managing G6PD deficiency?

A

Prevention strategies include:

Screening for G6PD deficiency
Avoiding known oxidative agents (such as certain drugs and foods)

151
Q

What is the role of reticulocytes in compensating for G6PD deficiency during a hemolytic episode?

A

Reticulocytes have higher levels of G6PD activity compared to mature RBCs, which helps mitigate the effects of the deficiency during a hemolytic episode.

152
Q

What is pyruvate kinase (PK) and its role in red blood cells?

A

Pyruvate kinase (PK) is a key enzyme of the glycolytic pathway. It catalyzes the conversion of phosphoenolpyruvate to pyruvate, forming ATP in red blood cells.

153
Q

What happens to red blood cells in pyruvate kinase (PK) deficiency?

A

In PK deficiency, there is a depletion of ATP, leading to a lack of membrane integrity, which causes premature destruction of red blood cells.

154
Q

What are the clinical presentations of pyruvate kinase (PK) deficiency?

A

Anemia
Jaundice
Splenomegaly
Gallstones (due to chronic hemolysis)
In neonates, this may present as severe anemia, while in adults, it ranges from severe to compensated anemia.

155
Q

How does pyruvate kinase (PK) deficiency affect ATP production in red blood cells?

A

PK deficiency impairs ATP production because PK catalyzes a critical step in glycolysis. Without sufficient ATP, red blood cells cannot maintain their membrane integrity, leading to hemolysis.

156
Q

What is the difference in severity between neonates and adults with pyruvate kinase (PK) deficiency?

A

In neonates, PK deficiency often presents as severe anemia, while in adults, the condition can range from severe to compensated anemia, depending on the individual.

157
Q

What are the complete blood count (CBC) findings in PK deficiency?

A

WBC count: normal or slightly increased
PLT count: normal or slightly increased
Hemoglobin: variable
Reticulocyte count: increased

158
Q

What biochemistry findings are associated with PK deficiency?

A

Serum haptoglobin: decreased
Serum indirect bilirubin: increased
Urine urobilinogen: increased

159
Q

What are the peripheral blood smear (PBS) findings in PK deficiency?

A

Anisocytosis
Poikilocytosis
Polychromasia
Burr cells

160
Q

What confirmatory tests are used to diagnose PK deficiency?

A

PK activity assay: decreased
Genetic testing: detects mutations in the PK gene

161
Q

What are the treatment options for PK deficiency?

A

Supportive treatment and transfusion (if required)
Splenectomy
Hematopoietic stem cell transplant (for severe disease, primarily in children)

162
Q

How does an increase in 2,3-bisphosphoglycerate (2,3 BPG) help patients with PK deficiency?

A

An increase in 2,3 BPG promotes greater release of oxygen at tissues, allowing the patient to tolerate lower hemoglobin levels.

163
Q

What is Paroxysmal Nocturnal Hemoglobinuria (PNH)?

A

PNH is a rare chronic intravascular hemolytic anemia caused by a mutation in a clonal hematopoietic stem cell, resulting in circulating blood cells that lack two surface markers: CD55 and CD59.

164
Q

What is the role of CD55 and CD59 in PNH?

A

CD55 and CD59 are complement-inhibiting proteins. Without these proteins, the cells cannot prevent activation of complement, leading to spontaneous and chronic intravascular hemolysis.

165
Q

What are common clinical findings associated with Paroxysmal Nocturnal Hemoglobinuria (PNH)?

A

Symptoms of anemia: fatigue, shortness of breath
Thrombosis: Budd-Chiari syndrome, deep vein thrombosis, pulmonary embolism, stroke
Smooth muscle dystonia: abdominal pain, dysphagia, erectile dysfunction, esophageal spasms
Dark urine
Jaundice

166
Q

What causes thrombosis in PNH?

A

Thrombosis in PNH is caused by intravascular hemolysis and platelet activation due to depletion of nitric oxide by free hemoglobin.

167
Q

What are the possible long-term effects of Paroxysmal Nocturnal Hemoglobinuria (PNH)?

A

Long-term effects of PNH include chronic kidney disease, renal tubule damage, and microvascular thrombosis due to repeated episodes of hemoglobinuria and platelet activation.

168
Q

What are the key biochemistry findings in PNH?

A

Serum haptoglobin: decreased
Plasma hemoglobin: increased
Serum indirect bilirubin: increased
Hemoglobinuria: present
Hemosiderinuria: present

169
Q

What peripheral blood findings are seen in PNH?

A

Reticulocyte count: increased
MCV: slightly elevated
Pancytopenia
Usually normochromic/normocytic
Iron deficiency anemia (IDA) due to urinary loss of iron
In acute crisis: fragments

170
Q

What bone marrow findings are common in PNH?

A

Normocellular to hypercellular
Erythroid hyperplasia

171
Q

What confirmatory tests are used for diagnosing PNH?

A

Ham’s Test
Sugar Water Test
Flow Cytometry

172
Q

What is hemoglobinuria, and how is it seen in PNH?

A

Hemoglobinuria in PNH is characterized by dark urine, especially in the morning, containing free hemoglobin from burst red blood cells. The urine generally clears as the day progresses.

173
Q

What is Eculizumab, and how does it work in the treatment of PNH?

A

Eculizumab is a monoclonal antibody against complement C5 that inhibits the formation of the membrane attack complex (MAC) in complement. This reduces hemolysis, leading to milder anemia and symptoms, but it is not a curative treatment for PNH.

174
Q

What is the role of Eculizumab in the management of PNH?

A

Eculizumab helps manage PNH by reducing hemolysis, resulting in milder anemia and fewer symptoms. However, it does not cure the condition.

175
Q

What supportive treatments are used in PNH?

A

Iron therapy to manage iron deficiency caused by hemolysis.
Anticoagulants to treat or prevent thrombotic complications.

176
Q

When is hematopoietic stem cell transplant used in the treatment of PNH?

A

Hematopoietic stem cell transplant is considered a curative treatment for PNH, typically reserved for severe cases where other treatments have been ineffective.

177
Q

Why are anticoagulants used in the treatment of PNH?

A

Anticoagulants are used to prevent or treat thrombotic complications, which are common in PNH due to increased risk of blood clots.

178
Q

What is immune hemolytic anemia?

A

Immune hemolytic anemia is a condition where red cell survival is shortened due to antibody-mediated mechanisms. Some antibodies can activate the complement system, leading to hemolysis.

179
Q

How are red blood cells (RBCs) removed in immune hemolytic anemia?

A

RBCs with antibodies or complement are removed by:

Macrophages (extravascular hemolysis)
Complement-mediated hemolysis (intravascular hemolysis)
A combination of both extravascular and intravascular processes

180
Q

How is immune hemolytic anemia classified?

A

Immune hemolytic anemia can be classified into:

Autoimmune hemolytic anemia
Alloimmune hemolytic anemia
Drug-induced immune hemolytic anemia

181
Q

What is the role of antibodies in immune hemolytic anemia?

A

In immune hemolytic anemia, antibodies attach to red blood cells, marking them for destruction by macrophages or leading to complement activation, which causes hemolysis.

182
Q

What are the two main processes involved in red blood cell destruction in immune hemolytic anemia?

A

Extravascular hemolysis, where macrophages remove antibody-coated RBCs.
Intravascular hemolysis, where complement leads to RBC destruction in the blood vessels.

183
Q

What are the two types of antibodies involved in most immune hemolytic anemias?

A

The two types of antibodies involved are:

IgM
IgG

184
Q

How does IgM-mediated hemolysis differ based on the amount of IgM on the RBC surface?

A

A small amount of IgM on the RBC surface cannot fully activate complement, and RBCs are destroyed by Kupffer cells in the liver (extravascular hemolysis).
A large amount of IgM can activate complement fully, resulting in rapid intravascular hemolysis.

185
Q

Where are RBCs removed in IgG-mediated hemolysis?

A

In IgG-mediated hemolysis, RBCs are predominantly removed by macrophages in the spleen and liver (extravascular hemolysis).

186
Q

What is the role of splenic macrophages in IgG-mediated hemolysis?

A

Splenic macrophages bind to antibodies attached to RBCs, leading to fragmentation of the RBC membrane and the formation of microspherocytes.

187
Q

What are the typical CBC findings in immune hemolytic anemia (HA)?

A

WBC count: possibly increased
Platelet count: possibly increased
Hemoglobin: decreased
Reticulocytes: increased

188
Q

What biochemical markers are seen in immune hemolytic anemia?

A

Serum haptoglobin: decreased
Serum unconjugated bilirubin: increased
Plasma hemoglobin: increased (intravascular hemolysis)
Hemoglobinuria and hemosiderinuria: signs of intravascular hemolysis

189
Q

What findings are typically observed on a peripheral blood smear (PBS) in immune hemolytic anemia?

A

Polychromasia
Spherocytes
Possible RBC agglutination
Nucleated RBCs
RBC fragments

190
Q

What is the purpose of the Direct Antiglobulin Test (DAT)?

A

DAT detects red blood cells sensitized with IgG in vivo, helping to confirm immune hemolytic anemia.

191
Q

What laboratory findings confirm immune hemolytic anemia?

A

Positive Direct Antiglobulin Test (DAT)

192
Q

What causes premature RBC destruction in autoimmune hemolytic anemia (AIHA)?

A

Premature RBC destruction in AIHA is caused by autoantibodies that bind to the RBC surface, with or without complement activation.

193
Q

How is autoimmune hemolytic anemia (AIHA) classified?

A

AIHA is divided into four categories:

Warm autoimmune hemolytic anemia (WAIHA)
Cold agglutinin disease
Paroxysmal cold hemoglobinuria
Mixed autoimmune hemolytic anemia (AIHA)

194
Q

What are the four categories of autoimmune hemolytic anemia (AIHA)?

A

Warm autoimmune hemolytic anemia (WAIHA)
Cold agglutinin disease
Paroxysmal cold hemoglobinuria
Mixed autoimmune hemolytic anemia

195
Q

What is the role of autoantibodies in autoimmune hemolytic anemia (AIHA)?

A

Autoantibodies in AIHA bind to RBCs, leading to their premature destruction, either by macrophages (extravascular hemolysis) or through complement activation (intravascular hemolysis).

196
Q

What type of immunoglobulin is associated with Warm Autoimmune Hemolytic Anemia (WAIHA)?

A

IgG is the immunoglobulin associated with Warm Autoimmune Hemolytic Anemia (WAIHA).

197
Q

At what temperature do autoantibodies in WAIHA show optimum reactivity?

A

Autoantibodies in WAIHA show optimum reactivity at 37°C.

198
Q

What type of hemolysis occurs primarily in Warm Autoimmune Hemolytic Anemia (WAIHA)?

A

Extravascular hemolysis is the primary type of hemolysis in WAIHA.

199
Q

What laboratory findings are associated with WAIHA?

A

Laboratory findings in WAIHA include polychromasia and spherocytes.

200
Q

What treatments are commonly used for WAIHA?

A

Common treatments for WAIHA include:

Glucocorticosteroid
Transfusion
Splenectomy
Rituximab
Hematopoietic stem cell transplantation

201
Q

How is sensitization detected in Warm Autoimmune Hemolytic Anemia?

A

Sensitization in WAIHA is detected by DAT (Direct Antiglobulin Test) showing IgG or IgG + complement.

202
Q

What immunoglobulin is involved in Cold Agglutinin Disease (CAD)?

A

IgM is the immunoglobulin involved in Cold Agglutinin Disease (CAD).

203
Q

At what temperature do autoantibodies in Cold Agglutinin Disease (CAD) have optimal reactivity?

A

Autoantibodies in CAD have optimal reactivity at 4°C.

204
Q

How is sensitization detected in Cold Agglutinin Disease (CAD)?

A

Sensitization in CAD is detected by the Direct Antiglobulin Test (DAT) through complement activation.

205
Q

What type of hemolysis occurs in Cold Agglutinin Disease (CAD)?

A

Hemolysis in CAD is primarily extravascular, but some intravascular hemolysis can occur if full complement activation takes place.

206
Q

What are the common laboratory findings in Cold Agglutinin Disease (CAD)?

A

Common laboratory findings in CAD include RBC agglutination and hemoglobinuria.

207
Q

What are the treatments for severe Cold Agglutinin Disease (CAD)?

A

Treatments for severe CAD include:

Transfusion
Supportive care
Rituximab
Plasmapheresis

208
Q

What immunoglobulin is involved in Paroxysmal Cold Hemoglobinuria (PCH)?

A

IgG is the immunoglobulin involved in Paroxysmal Cold Hemoglobinuria (PCH).

209
Q

At what temperature does the autoantibody in PCH have optimal reactivity?

A

The autoantibody in PCH has optimal reactivity at 4°C.

210
Q

How is sensitization detected in Paroxysmal Cold Hemoglobinuria (PCH)?

A

Sensitization in PCH is detected by the Direct Antiglobulin Test (DAT) through complement activation.

211
Q

What type of hemolysis occurs in Paroxysmal Cold Hemoglobinuria (PCH)?

A

Hemolysis in PCH is intravascular.

212
Q

Which antigen is associated with autoantibody specificity in PCH?

A

The autoantibody in PCH is specific to the P antigen on RBCs.

213
Q

What are the common laboratory findings in Paroxysmal Cold Hemoglobinuria (PCH)?

A

Laboratory findings in PCH include:

Polychromasia
Spherocytes
Schistocytes
NRBCs
Anisocytes
Poikilocytosis
Hemoglobinuria
Anti-P positive

214
Q

What is the typical treatment for Paroxysmal Cold Hemoglobinuria (PCH)?

A

Treatment for PCH is usually self-limiting, but in life-threatening anemia, a transfusion is provided until symptoms resolve.

215
Q

Which immunoglobulins are involved in Mixed-Type Autoimmune Hemolytic Anemia (HA)?

A

Both IgG and IgM are involved in Mixed-Type Autoimmune Hemolytic Anemia (HA).

216
Q

What is the optimal reactivity temperature of the autoantibodies in Mixed-Type Autoimmune HA?

A

The optimal reactivity temperature is between 4°C and 37°C.

217
Q

How is sensitization detected in Mixed-Type Autoimmune HA?

A

Sensitization is detected by the Direct Antiglobulin Test (DAT) through IgG and complement.

218
Q

Does complement activation occur in Mixed-Type Autoimmune HA?

A

Yes, complement activation occurs in Mixed-Type Autoimmune HA.

219
Q

What types of hemolysis are present in Mixed-Type Autoimmune HA?

A

Both intravascular and extravascular hemolysis occur in Mixed-Type Autoimmune HA.

220
Q

What is the autoantibody specificity in Mixed-Type Autoimmune HA?

A

The autoantibodies are panreactive in Mixed-Type Autoimmune HA.

221
Q

What is the general mechanism of hemolysis in Mixed-Type Autoimmune HA?

A

Patients develop both IgG and IgM autoantibodies, leading to a combination of extravascular and intravascular hemolysis.

222
Q

What are the two main types of Alloimmune Hemolytic Anemia?

A

Hemolytic Transfusion Reactions
Hemolytic Disease of the Fetus and Newborn (HDFN)

223
Q

What are Hemolytic Transfusion Reactions?

A

Hemolytic Transfusion Reactions are immune-mediated destruction of donor cells by an antibody in the recipient. There are two types: acute and delayed onset.

224
Q

What is Acute Hemolytic Transfusion Reaction (AHTR)?

A

AHTR occurs within minutes to hours after the initiation of transfusion, most commonly caused by the accidental transfusion of ABO-incompatible donor RBCs into a recipient.

225
Q

What causes Acute Hemolytic Transfusion Reactions?

A

Preformed IgM antibodies in the recipient target donor cells, causing complement-mediated intravascular hemolysis and activation of coagulation.

226
Q

What are the laboratory findings in Acute Hemolytic Transfusion Reaction (AHTR)?

A

Hemoglobinemia & hemoglobinuria
Decreased hemoglobin levels
Increased serum indirect bilirubin
Positive Direct Antiglobulin Test (DAT)
Decreased serum haptoglobin

227
Q

What is the treatment for Acute Hemolytic Transfusion Reactions?

A

Stop the transfusion
Investigation of the reaction
Supportive therapy for serious symptoms

228
Q

What is a Delayed Hemolytic Transfusion Reaction (DHTR)?

A

DHTR occurs days or weeks after a transfusion when a patient has been previously exposed to an antigen, generating an alloantibody that increases after re-exposure, leading to extravascular hemolysis.

229
Q

What causes Delayed Hemolytic Transfusion Reactions (DHTR)?

A

DHTR is caused by an alloantibody that was previously generated from an initial exposure to an antigen, which remained at undetectable levels. Upon re-exposure, the alloantibody increases and binds to transfused RBCs, leading to extravascular hemolysis.

230
Q

What are signs that a Delayed Hemolytic Transfusion Reaction (DHTR) has occurred?

A

Inadequate post-transfusion increase in hemoglobin
Positive Direct Antiglobulin Test (DAT) – IgG/complement
Morphologic evidence of hemolysis – polychromasia, spherocytes, etc.
Increase in serum unconjugated bilirubin

231
Q

What are the two types of Hemolytic Disease of the Fetus and Newborn (HDFN)?

A

Rh HDFN
ABO HDFN

232
Q

How does Hemolytic Disease of the Fetus and Newborn (HDFN) occur?

A

In HDFN, the IgG alloantibody produced by the mother crosses the placenta and binds to fetal red blood cells, causing anemia when these sensitized fetal cells are cleared by macrophages in the fetal spleen.

233
Q

What happens when fetal cells are destroyed in HDFN?

A

The destruction of fetal cells leads to anemia. To compensate, erythroid hyperplasia occurs in the fetal bone marrow and extramedullary erythropoiesis in fetal organs.

234
Q

What are the potential severe outcomes of Hemolytic Disease of the Fetus and Newborn (HDFN)?

A

If anemia is severe in utero, it can lead to generalized edema (hydrops fetalis) and death.

235
Q

How does Rh Hemolytic Disease of the Fetus and Newborn (Rh HDFN) develop?

A

Rh HDFN occurs when an Rh-negative mother carries an Rh-positive baby. Fetal Rh-positive blood cells enter the mother’s bloodstream, causing her to produce Rh antibodies. These antibodies attack the Rh-positive fetal blood cells during later pregnancies.

236
Q

What are the laboratory findings in Rh HDFN?

A

Decreased hemoglobin
Increased reticulocyte count
Peripheral Blood Smear (PBS): polychromasia and many nucleated RBCs (nRBCs)
Direct Antiglobulin Test (DAT): positive
Increased serum unconjugated bilirubin

237
Q

What is the treatment for Rh Hemolytic Disease of the Fetus and Newborn (Rh HDFN) before and after birth?

A

Before birth: Intrauterine transfusion
After birth: Exchange transfusion and phototherapy

238
Q

What is ABO Hemolytic Disease of the Fetus and Newborn (ABO HDFN)?

A

ABO HDFN is a milder form of hemolytic disease compared to Rh HDFN. It occurs because A and B antigens are poorly developed on newborn RBCs, and other cells and tissues express A and B antigens, reducing the maternal antibody’s effect on fetal RBCs.

239
Q

What are the typical laboratory findings in ABO HDFN?

A

Usually asymptomatic
Mild hyperbilirubinemia
Direct Antiglobulin Test (DAT) is weakly positive or negative
Peripheral Blood Smear (PBS): Polychromasia, spherocytes

240
Q

What is the difference in blood groups between Rh HDFN and ABO HDFN?

A

Rh HDFN: Mother is Rh (D) negative, Child is Rh (D) positive.
ABO HDFN: Mother is blood group O, Child is blood group A or B.

241
Q

How does the severity of the disease differ between Rh and ABO HDFN?

A

Rh HDFN: Severe disease.
ABO HDFN: Mild disease.

242
Q

How does jaundice present in Rh HDFN vs ABO HDFN?

A

Rh HDFN: Jaundice is severe.
ABO HDFN: Jaundice is mild.

243
Q

What is the difference in the presence of spherocytes on the peripheral blood film between Rh and ABO HDFN?

A

Rh HDFN: Spherocytes are rare.
ABO HDFN: Spherocytes are usually present.

244
Q

How does anemia differ in Rh HDFN vs ABO HDFN?

A

Rh HDFN: Anemia is severe.
ABO HDFN: If present, anemia is mild.

245
Q

What are the Direct Antiglobulin Test (DAT) results in Rh and ABO HDFN?

A

Rh HDFN: DAT is positive.
ABO HDFN: DAT is negative or weakly positive.

246
Q

What is Drug-Induced Hemolytic Anemia (DIIHA)?

A

DIIHA is a condition where red blood cells (RBCs) are destroyed due to an immune response triggered by a drug. It can lead to both extravascular and intravascular hemolysis.

247
Q

What are the three mechanisms of Drug-Induced Hemolytic Anemia?

A

Drug adsorption: The drug binds strongly to the RBC, and antibodies target the drug, leading to extravascular hemolysis.

Drug-RBC membrane protein immunogenic complex: The drug forms a complex with the RBC membrane protein, causing complement activation and acute intravascular hemolysis.

RBC autoantibody induction: The drug stimulates the production of autoantibodies to RBC antigens, leading to extravascular hemolysis.

248
Q

When should Drug-Induced Hemolytic Anemia (DIIHA) be suspected?

A

DIIHA should be suspected when there is a decrease in hemoglobin after:

Administration of a drug
Clinical and biochemical evidence of extravascular or intravascular hemolysis
A positive Direct Antiglobulin Test (DAT)

249
Q

What is the result of the Direct Antiglobulin Test (DAT) in Drug-Induced Hemolytic Anemia?

A

The Direct Antiglobulin Test (DAT) is positive in cases of DIIHA.

250
Q

What are the two general types of antibodies implicated in drug-induced immune hemolytic anemia?

A

Drug-dependent antibodies:
Antibodies that react only with drug-treated cells.
Antibodies that react only in the presence of the drug.

Drug-independent antibodies

251
Q

What are the two types of drug-dependent antibodies in drug-induced immune hemolytic anemia?

A

Antibodies that react only with drug-treated cells.
Antibodies that react only in the presence of the drug.

252
Q

What is the treatment for Drug-Induced Immune Hemolytic Anemia (DIIHA)?

A

Stop administering the drug.
For severe anemia, consider transfusion or plasma exchange.
Avoid the drug in the future.

Hematology (6 decks)

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