Hemolytic Anemia

Question 1

Elevated Reticulocytes Indicate..

Answer 1

Hemoglobinopathies
• RBC Membrane
Defects
• Enzyme deficiencies

Question 2

Decreased Recitulocytes indicate…

Answer 2

Fe deficiency
• Lead poisoning
• Inflammation
• Bone marrow failure
syndromes

Question 3

Two definitions of Hemolytic Anemia

Answer 3

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

Question 4

Two types of etiology of hemolytic anemia

Answer 4

Intrinsic abnormalities ( most often congenital)
Membrane, enzymes, hemoglobin

Extrinsic forces ( most often acquired)
Antibodies, toxins, mechanical stress

Question 5

Two types of hemolysis

Answer 5

Intravascular

Extravascular

Question 6

Hemolytic Anemia History (Hx): look for:

Answer 6

• 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

Question 7

Hemolytic Anemia Signs/Sx:

Answer 7

Pallor, fatigue
Jaundice, dark urine
Splenomegaly, gallstones

Question 8

Hemolytic Anemia Lab Findings

Answer 8

Reticulocytosis, 
Anemia
Elevated bilirubin
Elevated AST > ALT
Elevated LDH

Question 9

Hemolytic Anemia Intrinsic Causes:

Answer 9

Membrane disorders: Spherocytosis, Eliptocytosis, Pyropoikilocytosis

Enzyme disorders: G6PD Deficiency, Pyruvate Kinase Deficiency

Hemoglobin disorders

Question 10

Hereditary Spherocytosis (HS) Characteristics

Answer 10

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

Question 11

Hereditary Spherocytosis Clinical Signs/Sx

Answer 11

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

Question 12

Parvovirus B19 infection Characteristics

Answer 12

• “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)

Question 13

Hereditary Spherocytosis Levels of Infection

Answer 13

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

Question 14

Hereditary Spherocytosis Lab Findings

Answer 14

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

Question 15

Hereditary Spherocytosis Diagnostic Test results

Answer 15

Negative Direct Antiglobulin Test (DAT/Coombs)

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

Question 16

Osmotic Fragility Testing:

Answer 16

*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

Question 17

Hereditary Elliptocytosis (HE) Characteristics:

Answer 17

• 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%

Question 18

Hereditary Pyropoikilocytosis (HPP) Characteristics:

Answer 18

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

Question 19

Normal RBC Metabolism Characteristics

Answer 19

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

Question 20

RBC Enzyme Disorders Characteristics:

Answer 20

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

Question 21

Two Kinds of Genetics of RBC Enzyme Disorders

Answer 21

Autosomal recessive inheritance: Majority of congenital RBC enzyme disorders

X-linked inheritance

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

Question 22

Pyruvate Kinase Deficiency Characteristics:

Answer 22

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

Question 23

G6PD Deficiency Characteristics

Answer 23

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

Question 24

G6PD Deficiency Signs/Sx:

Answer 24

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

Question 25

G6PD Deficiency Diagnostic Lab findings:

Answer 25

• 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

Question 26

Medical Management of Congenital | Hemolytic Anemia

Answer 26

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

Question 27

Splenectomy For Hemolytic Anemia Considerations:

Answer 27

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

Question 28

Post-Splenectomy Complications:

Answer 28

Overwhelming post-splenectomy infection (OPSI) • Typically encapsulated organisms • Immunizations, Antibiotic prophylaxis • Fever precautions Resistant pneumococcal and meningococcal disease Thrombotic Events Pulmonary Hypertension

Question 29

DDX: Erythrocyte Membrane Disorders vs Enzyme Disorders

Answer 29

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

Question 30

Hemolytic Anemia Extrinsic Etiologies:

Answer 30

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)

Question 31

Autoimmune Hemolytic Anemia (AIHA) characteristics:

Answer 31

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)

Question 32

Warm-Reactive AIHA characteristics:

Answer 32

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

Question 33

Direct Antiglobulin Test (DAT) | AKA “Coombs Test”: How does it work?

Answer 33

``` Sensitized Erythrocytes + Coombs reagent (anti-IgG, anti-C3) = Visual RBC Agglutination (1+ to 4+) ```

Question 34

Warm-Reactive AIHA Signs/Sx:

Answer 34

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

Question 35

Warm-Reactive AIHA Labs:

Answer 35

``` • Anemia and reticulocytosis • Spherocytes on peripheral blood smear • Positive DAT + IgG, ± Complement (C3) ```

Question 36

Warm-Reactive AIHA

Answer 36

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

Question 37

Problems with Long-term Steroids:

Answer 37

``` Weight gain Diabetes Osteoporosis and fracture Osteonecrosis of the femoral head Cataracts ```

Question 38

Cold Agglutinin Disease (Cold Reactive AIHA) Characteristics:

Answer 38

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

Question 39

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

Answer 39

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

Question 40

Cold Agglutinin Disease (Cold Reactive AIHA) Labs:

Answer 40

• 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

Question 41

Cold Agglutinin Disease (Cold Reactive AIHA) Treatment

Answer 41

Largely symptomatic--Avoid cold! Rituximab re active or relapsing symptomatic hemolysis Splenectomy and corticosteroids ineffective so avoid If transfusion is needed—Warm the RBCs!

Question 42

DDX re Warm-Reactive AIHA vs Cold-Reactive AIHA

Answer 42

``` 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 ```

Question 43

Treatment Takeaways re Hemolytic Anemias

Answer 43

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