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Hemolytic Anemia > Hemolytic Anemia > Flashcards

Hemolytic Anemia Flashcards

1
Q

Elevated Reticulocytes Indicate..

A

Hemoglobinopathies
• RBC Membrane
Defects
• Enzyme deficiencies

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2
Q

Decreased Recitulocytes indicate…

A 
Fe deficiency
• Lead poisoning
• Inflammation
• Bone marrow failure
syndromes
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3
Q

Two definitions of Hemolytic Anemia

A

Increased RBC destruction
• Premature death, accelerated destruction

Increased RBC production
• Fully or partially compensated anemia
• Can have hemolysis without being anemic if the rate of red cell
production is brisk enough to keep up with the rate of destruction

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4
Q

Two types of etiology of hemolytic anemia

A 
Intrinsic abnormalities ( most often congenital)
Membrane, enzymes, hemoglobin
Extrinsic forces ( most often acquired)
Antibodies, toxins, mechanical stress
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5
Q

Two types of hemolysis

A

Intravascular

Extravascular

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6
Q

Hemolytic Anemia History (Hx): look for:

A
  • Sex: G6PD (enzyme disorder) is X-linked
  • Race/Ethnicity: Hemoglobinopathies
  • Personal and Family History: Previous counts, Neonatal jaundice, History of required transfusion, Early gallstones, Splenomegaly/Splenectomy
  • Drugs
  • Infections/Illnesses: AIHA, Parvovirus B19—aplastic event
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7
Q

Hemolytic Anemia Signs/Sx:

A

Pallor, fatigue
Jaundice, dark urine
Splenomegaly, gallstones

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8
Q

Hemolytic Anemia Lab Findings

A 
Reticulocytosis, 
Anemia
Elevated bilirubin
Elevated AST > ALT
Elevated LDH
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9
Q

Hemolytic Anemia Intrinsic Causes:

A

Membrane disorders: Spherocytosis, Eliptocytosis, Pyropoikilocytosis

Enzyme disorders: G6PD Deficiency, Pyruvate Kinase Deficiency

Hemoglobin disorders

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10
Q

Hereditary Spherocytosis (HS) Characteristics

A

Spherocytes: smaller, loss of central pallor

Congenital hemolytic anemia
• Most common inherited anemia in individuals of
northern European descent 
• Autosomal Dominant Inheritance
• ~1/3 are spontaneous mutations

Mutations affect RBC membrane
• Spectrin, ankyrin
• Loss of membrane surface area relative to intracellular
volume

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11
Q

Hereditary Spherocytosis Clinical Signs/Sx

A

Neonatal jaundice
• First 24 hours of life
• Exaggerated, prolonged physiologic nadir

Outside the newborn period:
• Incidental Laboratory findings
• Acute aplastic event (Parvovirus B19)
• Jaundice, Splenomegaly, early gallstones

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12
Q

Parvovirus B19 infection Characteristics

A
  • “5th Disease”
  • Clinical manifestations: URI/pharyngitis, rash (“slapped cheeks”), Very mild anemia
  • Infects RBC precursors for 7-10 days so rapid decrease in red calls daily
  • Dx: serology (IgM)
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13
Q

Hereditary Spherocytosis Levels of Infection

A

Depends on Spectrin Content:

Mild HS: 20-30% of cases, No anemia, sight Reticulocyte increase, Mild jaundice

Moderate HS: 65-75% of cases, + anemia, +Reticulocytes, + Bilirubin, ± splenomegaly, Occasional transfusions

Severe HS: 5% of cases, ++ anemia, ++Reticulocytes, ++ Bilirubin, Marked splenomegaly, Regular transfusions

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14
Q

Hereditary Spherocytosis Lab Findings

A

Anemia
Reticulocytosis
*MCHC typically > 36%
Wide RDW (small spheres and large reticulocytes)
Often elevated bilirubin, LDH, AST>ALT
*Presence of spherocytes on peripheral blood smear

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15
Q

Hereditary Spherocytosis Diagnostic Test results

A

Negative Direct Antiglobulin Test (DAT/Coombs)

Positive Osmotic Fragility Testing: decreased surface area means no room to swell so burst.

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16
Q

Osmotic Fragility Testing:

A

*Tests RBC integrity with varying osmotic loads

Endpoint is in vitro hemolysis

Difficulties in interpretation
 Transfused cells, high reticulocyte count
 Young age (< 6 - 12 months)

Does not differentiate congenital vs. acquired
spherocytes

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17
Q

Hereditary Elliptocytosis (HE) Characteristics:

A
  • Elliptical, cigar shaped, erythrocytes
  • Normochromic, normocytic, may or may not be anemic
  • Defect in spectrin
  • African and Southeast Asian Variants: 1:100 in parts of Africa
  • Autosomal Dominant
  • Many asymptomatic: RBC lifespan decreased by only ~10%
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18
Q

Hereditary Pyropoikilocytosis (HPP) Characteristics:

A

• Newborns with severe hemolytic anemia:
– Anemia, jaundice
– Poikilocytosis, elliptocytosis, and spherocytosis
– Fragments of cells so intra & extravascular lysis
• Gradually evolves into mild HE

19
Q

Normal RBC Metabolism Characteristics

A

Absence of nucleus, mitochondria, ribosomes

Anaerobic metabolism: Glycolysis for ATP production

  • Facilitated transfer of glucose
  • Embden-Meyerhof pathway for energy (ATP)
  • Rapoport-Luebering clutch (2,3 DPG)
  • HMP shunt for reducing power (NADPH, glutathione)

Energy needs and Enzymatic activities decline with time

  • Maintenance of cation gradients (Na/K pump)
  • Protection from oxidative damage
  • Maintenance of 2+ ferrous iron (NADH)
  • Production of 2,3 DPG for oxygen unloading
  • Nucleotide salvage and conservation
20
Q

RBC Enzyme Disorders Characteristics:

A

Inherited defects in the metabolic pathway

Effects on the erythrocytes:

  • Shortened in vivo lifespan,
  • Congenital non-spherocytic hemolytic anemia
  • Intravascular versus extravascular hemolysis

Effects other cells: Leukocytes, liver, brain

21
Q

Two Kinds of Genetics of RBC Enzyme Disorders

A

Autosomal recessive inheritance: Majority of congenital RBC enzyme disorders

X-linked inheritance

  • Glucose 6 Phosphate (G6PD) Deficiency
  • Phosphoglycerate kinase (PGK) deficiency
22
Q

Pyruvate Kinase Deficiency Characteristics:

A

Autosomal recessive disorder affecting RBC, WBC, liver

Non-spherocytic hemolytic anemia with:

  • Hemolysis
  • Reticulocytosis
  • Elevated LDH, Bili, hemoglobinuria
  • Polychromasia, ecchinocytes, acanthocytes

Decreased synthesis of ATP
-Increased 2,3 DPG levels cause O2 release at low hemoglobin concentrations

Partial response after splenectomy

23
Q

G6PD Deficiency Characteristics

A

Most common human genetic mutation: X-linked

High prevalence re malaria protection

> 400 missense Genetic mutations:
A- variant most common among African descent
Mediterranean variant more severe

Effects of G6PD deficiency
Incomplete protection against oxidative stress

Acute hemolytic anemia after exposure to oxidative stress:
  Infections
  Sulfa drugs
  Naphthalene (moth balls)
  Fava beans
24
Q

G6PD Deficiency Signs/Sx:

A

Acute fatigue, jaundice, pallor,
dark urine (intravascular hemolysis),
+/- history of known trigger

25
Q

G6PD Deficiency Diagnostic Lab findings:

A

• Normocytic, normochromic anemia
• Reticulocytosis
• Elevated LDH, Bilirubin
** Hemoglobinuria (+ for blood, no RBCs on microscopic urine)
** Blister cells, anisocytosis on blood smear
**Assay G6PD activity after resolution of a hemolytic crisis

26
Q

Medical Management of Congenital

Hemolytic Anemia

A

Periodic medical visits
Education re: signs/symptoms of anemia and hemolysis
Examination for growth (children), icterus, splenomegaly
Blood counts for hemoglobin, reticulocytes
Anticipatory guidance for gallstones, splenomegaly, and
parvovirus B19 infection

Therapeutic intervention
Folic acid supplementation (+/-)
Erythrocyte transfusions BUT can cause poor growth,
cardiovascular compromise

Consider full/partial Splenectomy risk/benefits

27
Q

Splenectomy For Hemolytic Anemia Considerations:

A

Indications: Splenomegaly, hypersplenism, gallstones, jaundice, Growth, transfusion dependence

Methods
Partial versus total splenectomy procedure
Open versus laparoscopic procedure

**Pre-operative immunizations

Outcomes:
Laboratory improvement
Alleviation of transfusion dependence
Prevention of gallstone formation

28
Q

Post-Splenectomy Complications:

A

Overwhelming post-splenectomy infection (OPSI)
• Typically encapsulated organisms
• Immunizations, Antibiotic prophylaxis
• Fever precautions

Resistant pneumococcal and meningococcal
disease

Thrombotic Events

Pulmonary Hypertension

29
Q

DDX: Erythrocyte Membrane Disorders vs Enzyme Disorders

A

Erythrocyte Membrane Disorders: Spherocytes, Autosomal Dominant, Osmotic Fragility, Splenectomy: Complete response

Erythrocyte Enzyme Disorders: No Spherocytes,
Autosomal Recessive, No Osmotic Fragility, Splenectomy: Partial response

30
Q

Hemolytic Anemia Extrinsic Etiologies:

A

Erythrocyte Alloantibodies:
Neonatal alloimmune hemolysis
Post-transfusion exposure

Erythrocyte Autoantibodies:
Warm-reactive IgG antibodies
Cold-reactive IgG antibodies (PCH)
Cold agglutinin disease

External forces:
Schistocytic anemia,
Drugs, toxins, burns
Complement (PNH)

31
Q

Autoimmune Hemolytic Anemia (AIHA) characteristics:

A

Incidence: 1 - 3/100,000, children and adults

Variable clinical course: self-limited, short illness, waxing and waning, chronic illness

Prognosis typically good: Morbidity from treatment, Mortality <10%

Erythrocyte autoantibodies: IgG, IgM, Complement fixation

Types: Warm vs. Cold

Lab Test: Direct Antiglobulin Test (Coombs test)

32
Q

Warm-Reactive AIHA characteristics:

A

IgG autoantibody mediated RBC destruction
(G for Georgia = Warm)
• Bind RBC surface at warmer temperatures
* Extravascular hemolysis—Fc Receptors in the spleen
• Occasionally fix complement leading to lysis

Types:

  • Idiopathic
  • Immunodeficiency
  • Secondary: EBV infection
33
Q

Direct Antiglobulin Test (DAT)

AKA “Coombs Test”: How does it work?

A 
Sensitized Erythrocytes
\+
Coombs reagent (anti-IgG, anti-C3) 
=
Visual RBC Agglutination (1+ to 4+)
34
Q

Warm-Reactive AIHA Signs/Sx:

A
  • Typically rapid onset anemia
  • Can be life threatening
  • Fatigue, dyspnea, heart failure
  • Scleral Icterus, Jaundice, +/- dark urine (hemoglobinuria)
  • Splenomegaly
35
Q

Warm-Reactive AIHA Labs:

A 
• Anemia and reticulocytosis
• Spherocytes on peripheral blood smear
• Positive DAT
\+ IgG, 
± Complement (C3)
36
Q

Warm-Reactive AIHA

A

Transfusion will not be 100% compatible but may be necessary (Least Incompatible)

Glucocorticoids: Once remission has been achieved, wean steroids SLOWLY and mimic physiologic dosing as much as possible (AM dosing)

Splenectomy

Rituximab: Monoclonal antibody directed against CD20 on B-cell surface

37
Q

Problems with Long-term Steroids:

A 
Weight gain
Diabetes
Osteoporosis and fracture
Osteonecrosis of the femoral head
Cataracts
38
Q

Cold Agglutinin Disease
(Cold Reactive AIHA)
Characteristics:

A

IgM-mediated RBC destruction (M for Minnesota = Cold)
• Agglutinins, Hemolysins

Pathophysiology: IgM binds and fixes complement to red cell in areas with cooler circulation, red cell returns to warmer circulation, then IgM dissociates but leaves complement (C3) leading to cell lysis

Kupffer cells in the liver have receptor for C3b

Etiology: Most idiopathic, some after mycoplasma or viral infection

39
Q

Cold Agglutinin Disease
(Cold Reactive AIHA)
Signs/Sx:

A

Erythrocyte agglutination upon exposure to cold
• Mottled or numb fingers and toes
• Acrocyanosis (blue extremities)

40
Q

Cold Agglutinin Disease
(Cold Reactive AIHA)
Labs:

A

• Mild anemia with reticulocytosis

** Red cell agglutination on PBS made at room temperature (but not at 37 C)!

** DAT (Coombs) will be positive for complement (C3) only

41
Q

Cold Agglutinin Disease
(Cold Reactive AIHA)
Treatment

A

Largely symptomatic–Avoid cold!

Rituximab re active or relapsing symptomatic hemolysis

Splenectomy and corticosteroids ineffective so avoid

If transfusion is needed—Warm the RBCs!

42
Q

DDX re Warm-Reactive AIHA vs Cold-Reactive AIHA

A 
Warm-Reactive AIHA:  IgG, 
  DAT result: +IgG, ± C3 (C3 fixation Variable)
  Thermal reactivity 37C,  
  RBC destruction: Spleen, 
  Tx: Steroids, Splenectomy 
Cold-Reactive AIHA: IgM
  Thermal reactivity: 4C
   \+C3 (C3 fixation)
  RBC destruction: Liver
  Common therapy: Avoid cold, Rituximab
43
Q

Treatment Takeaways re Hemolytic Anemias

A
  • NEVER withhold RBC transfusions if needed
  • Corticosteroid therapy must be weaned slowly
  • Limited utility of IVIG
  • Immunizations before splenectomy
  • Increasing use of rituximab therapy

Hemolytic Anemia (1 decks)

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