Hemolytic Anemias

Diagnosis

Indications for Testing

• Deformed and fragmented erythrocytes on peripheral smear; suspicion of hemolysis based on clinical presentation
  • Increased reticulocytosis, LD and bilirubin
  • Decreased haptoglobin

Laboratory Testing

• CBC with peripheral smear – initial screening
  • Platelet count
    • Decreased – consider DIC, HELLP, TTP, HUS
      • Order D-dimer, ADAMTS activity
    • Normal – consider vasculitis, mechanical factors
  • Cells noted may help diagnosis
    • Spherocytes – hereditary spherocytosis, elliptocytosis, immune-mediated hemolytic anemias
      • Consider testing for osmotic fragility
        • (+) – membrane defect
        • (+) acquired – direct Coombs
    • Schistocytes/fragmented cells – microangiopathic
    • Polychromasia without morphologic abnormality
      • Consider testing for one or more of the following: pyruvate kinase, hexokinase, glucose phosphate isomerase
    • Sickle cells – consider testing for HPLC
      • Abnormal red cells such as sickle cells, target cells may indicate hemoglobinopathy
    • Stomatocytes – hereditary stomatocytosis likely
    • Basophilic stippling levels
      • Acquired – lead levels
      • Non-acquired – 5’ nucleotidase test
    • Heinz body stain positive – suggests hereditary hemoglobinopathies, G6PD deficiency
      • Consider G6PD testing or isopropanol heat stability of the signals
    • Agglutination
      • Consider testing for direct Coombs (+) – cold agglutinin disease (C3d+ only); warm autoimmune hemolytic anemia (IgG+/C3d-)
    • Polychromasia only with possible lowered pH
      • Consider PNH testing
    • Unusual red cell inducers
      • If infection suspected – consider evaluation for Babesia, malaria
• Reticulocyte count – usually elevated; does not give specific diagnosis

Differential Diagnosis

• See classification in Clinical Background

Clinical Background

Hemolytic anemias result from premature destruction of red blood cells (RBCs). For information on types of hemolytic anemias, refer to the following topics

• Hemoglobinopathies
• Unstable hemoglobinopathies
• Thalassemias

Epidemiology

• Prevalence
  • Prevalence depends on etiology of hemolysis
    • Common – autoimmune hemolytic anemia, glucose-6 phosphate dehydrogenase (G6PD), pyruvate kinase (PK), hereditary spherocytosis (HS)
    • Rare – paroxysmal nocturnal hemoglobinuria (PNH)
• Sex – M:F, equal
• Ethnicity – higher prevalence of G6PD deficiency in Africans and persons of Mediterranean descent; sickle cell most often found in Africans

Classification

• Molecular defect hemoglobinopathies
  • Sickle cell anemia and other qualitative hemoglobin disorders
  • α-thalassemia, β-thalassemia
• Abnormality in RBC membrane structure or RBC enzymatic defects  
  • G6PD
  • PK deficiency
  • HS, stomatocytosis  
  • Hereditary PNH
• Environmental factors (physical disruption) or antibodies
  • Autoimmune (acquired) cold agglutinin
  • Drug-induced
  • Warm antibody-induced
  • Lymphoproliferative disorder or disseminated malignancy
    • Chronic lymphocytic leukemia
  • Mechanical valves
  • Microangiopathic red cell destruction
    • Thrombotic thrombocytopenic purpura (TTP) and hemolytic uremia syndrome (thrombotic microangiopathies)
    • Disseminated intravascular coagulation (DIC)
    • HELLP syndrome (Hemolysis, Elevated Liver enzyme levels, Low Platelet count)
• Infectious  
  • Cytomegalovirus
  • Epstein-Barr virus
  • Hepatitis C
  • HIV
  •  Leptospira
  • Plasmodium spp
  •  Mycoplasma pneumoniae
  • Toxins

Pathophysiology

• Processes cause breaking up (hemolysis) of RBCs into various sizes and shapes
• Manifested by elevated reticulocyte counts, low or absent haptoglobin levels, and variable presence of hemosiderin in urine
• Peripheral blood smear demonstrates evidence of RBC fragmentation, including spherocytes, target cells and Howell-Jolly bodies

Clinical Presentation of Specific Hemolytic Disorders

• Cell membrane disorders (mechanical weakness or fragility of erythrocyte membrane skeleton)
  • Hereditary spherocytosis
    • Prevalence – 1/2,000 in Caucasians
    • Inheritance – autosomal dominant
      • May involve mutations in ankyrin and spectrum – 75% of cases
      • Autosomal recessive or de novo mutations – 25% of cases
    • Clinical presentation
      • Range of severity from asymptomatic to severe disease
      • Anemia, splenomegaly, jaundice, gall stones (particularly in pediatric cases)
      • Reticulocytosis (after prior anemia)
  • Hereditary elliptocytosis
    • Incidence – 1-2/10,000 in Caucasians
    • Inheritance – autosomal dominant
      • Involves spectrin and some band mutations
    • Clinical presentation
      • Usually no significant hemolysis; may be asymptomatic
  • Hereditary stomatocytosis
    • Incidence – 1/50,000 in Caucasians
    • Inheritance – autosomal dominant
    • Clinical presentation – asymptomatic to moderately severe disease
• RBC enzyme defects
  • G6PD deficiency
    • Incidence
      • >400 million worldwide (most common enzyme deficiency worldwide)
      • Ethnicity – frequent in persons of African descent
        • 50% in Kurdish Jewish males
        • 0.1% in northern Europeans
    • Inheritance
      • X-linked recessive
      • ~350 different mutations
      • Mutation protects against malaria
    • Clinical presentation
      • Most patients are asymptomatic
      • Patients may present with fatigue, back pain, anemia, and jaundice as an indicator of hemolysis
        • Hemolysis occurs when patient is exposed to environmental stressors
          • Viral and bacterial infections (most common)
          • Many oxidative stressors secondary to drug exposure, most commonly sulfa, nitrofurantoin, antimalarials, toluidine blue, methylene blue
  • Pyruvate kinase deficiency
    • Incidence
      • 1/20,000 in Caucasians
      • Most common cause of congenital non-spherocytic hemolytic anemia
    • Inheritance
      • Autosomal recessive
      • More common in the Mediterranean population
      • Carriers are recognized by erythrocytes – PK activity ~50% of normal
      • >180 different mutations
    • Clinical presentation
      • Degree of hemolysis varies from mild to life-threatening neonatal anemia and jaundice, necessitating exchange transfusion
• Acquired hemolytic anemias – immune-mediated
  • Incidence – 1-3/100,000 annually
  • Age – more common in women during 4th and 5th decades
  • Common types
    • Warm antibody disease and cold reactive antibody disease
    • Usually caused by IgG or IgM antibodies reacting to RBCs
  • Clinical presentation
    • Warm antibody – generally directed broadly against Rh antigens
      • Symptoms usually a result of anemia
      • Slow, insidious onset
      • May have jaundice
    • Cold agglutinin hemolysis
      • 90% of patients have monoclonal B-cell lymphoproliferative bone marrow disorders 
      • Episodic acute hemolysis with hemoglobinuria
      • Acrocyanosis in response to cold and vasoocclusive phenomena of the fingers, toes, ears and nose present in some patients
    • Drugs – immune-mediated
      • Severity depends on the drug
      • Varies from mild to severe hemolysis
      • Most common drugs implicated – cephalosporins, NSAIDs
• Paroxysmal cold hemoglobinuria
  • Incidence –  rare
  • Median age – 5 years
  • Caused by a biphasic antibody (Donath-Landsteiner antibody)
  • Clinical presentation
    • Pallor, hemoglobinuria and mild jaundice
    • Patients usually have a history of recent viral infection

Indications for Laboratory Testing

• Tests generally appear in the order most useful for common clinical situations
• Click on number for test-specific information in the ARUP Laboratory Test Directory

Click the plus sign to expand the table of additional tests.

Test Name and Number	Comments
Haptoglobin 0050280 Method: Quantitative Immunoturbidimetry	Assess presence of intravascular hemolysis
Hemoglobin, Plasma 0020058 Method: Quantitative Spectrophotometry	Increase concentration indicative of acute intravascular destruction of erythrocytes Not of clinical value in the diagnosis of chronic hemolytic disorders
Hematocrit 0040080 Method: Automated Cell Count	Assess presence of anemia
Hemosiderin, Urine 0020222 Method: Semi-Quantitative Microscopy	Order for suspected intravascular hemolysis within the past week
Donath Landsteiner 0013039 Method: Hemolysis	Determine if Donath-Landsteiner antibodies are present  Diagnose paroxysmal cold hemoglobinuria
Blood Group (ABO & 8 Minor Antigens) Genotyping by Microarray 2004739 Method: Polymerase Chain Reaction/ASH Microarray	Patients with multiple transfusions with or without subsequent hemolytic reaction
Blood Group (9 Minor Antigens) Genotyping by Bead Array 2004743 Method: Polymerase Chain Reaction/Bead Array	Patients with multiple transfusions with or without subsequent hemolytic reaction
Blood Group (5 Minor Antigens) Genotyping by Bead Array 2004741 Method: Polymerase Chain Reaction/Bead Array	Patients with multiple transfusions with or without subsequent hemolytic reaction

Diagnostic Algorithm

  Hemolytic Anemias Testing Algorithm