What is a comprehensive, evidence‑based review of hemolytic anemia in children covering definition, epidemiology, pathophysiology, risk factors, classification (intravascular vs extravascular, inherited vs acquired), detailed causes and differentials, typical presentation, complications, detailed history and physical examination, diagnostic investigations and criteria with abnormal test results, initial weight‑based management, ongoing management of relapse and complications, and prognosis/follow‑up according to up‑to‑date AAP and CPS guidelines?

Comprehensive Review of Hemolytic Anemia in Pediatrics

Definition

Hemolytic anemia is the premature destruction of red blood cells (RBCs) before their normal 120-day lifespan, resulting in anemia when bone marrow compensatory mechanisms cannot match the rate of RBC loss. 1 The condition manifests with reticulocytosis, elevated lactate dehydrogenase (LDH), increased unconjugated bilirubin, and decreased haptoglobin levels. 1

Epidemiology

• Autoimmune hemolytic anemia (AIHA) represents a rare condition in children, differing significantly from adult presentations. 2
• Warm AIHA accounts for 60-70% of all AIHA cases, while cold agglutinin disease (CAD) represents 20-25%, with mixed forms and paroxysmal cold hemoglobinuria comprising 5-10%. 3
• Hereditary spherocytosis occurs in approximately 1 in 2,000 to 5,000 individuals of Northern European descent. 4
• Glucose-6-phosphate dehydrogenase (G6PD) deficiency affects over 400 million people worldwide, with higher prevalence in males due to X-linked inheritance. 4
• Sickle cell disease predominantly affects individuals of African, Mediterranean, Middle Eastern, and Indian ancestry. 4

Pathophysiology

Mechanisms of Hemolysis

Hemolysis occurs through multiple distinct mechanisms: 1

• Poor RBC deformability leading to splenic trapping and phagocytosis
• Antibody-mediated destruction through phagocytosis or direct complement activation
• Mechanical fragmentation from microthrombi or direct trauma
• Oxidative damage to RBC membranes and hemoglobin
• Direct cellular destruction from infectious agents or toxins

Site of Destruction

Extravascular hemolysis (predominant mechanism): 1

• Occurs in the reticuloendothelial system (spleen, liver, bone marrow)
• Antibody-coated or damaged RBCs are phagocytosed by macrophages
• Results in unconjugated hyperbilirubinemia, elevated LDH, and decreased haptoglobin
• Splenomegaly and jaundice are common findings

Intravascular hemolysis (less common, more severe): 1

• Direct RBC destruction within blood vessels
• Releases free hemoglobin into plasma
• Causes hemoglobinuria, hemoglobinemia, and more profound haptoglobin depletion
• Associated with complement-mediated destruction, mechanical trauma, or severe oxidative stress

Risk Factors

For Immune-Mediated Hemolysis 2, 5

• Underlying lymphoproliferative disorders
• Systemic autoimmune diseases (systemic lupus erythematosus, rheumatoid arthritis)
• Congenital immunodeficiencies
• Recent infections (Mycoplasma pneumoniae, Epstein-Barr virus, cytomegalovirus)
• Medication exposure (penicillins, cephalosporins, immune checkpoint inhibitors)
• Hematopoietic stem cell transplantation

For Hereditary Hemolytic Anemias 4

• Family history of anemia, jaundice, or splenectomy
• Ethnic background (Mediterranean, African, Southeast Asian ancestry)
• Consanguinity
• Neonatal jaundice requiring phototherapy or exchange transfusion

For Acquired Non-Immune Hemolysis 1

• Exposure to oxidative stressors (fava beans, naphthalene, certain medications in G6PD deficiency)
• Infections (malaria, babesiosis, Clostridium perfringens)
• Microangiopathic conditions (hemolytic uremic syndrome, thrombotic thrombocytopenic purpura)
• Mechanical heart valves or cardiac devices

Classification

Intravascular vs. Extravascular Hemolysis

Intravascular hemolysis characteristics: 1

• Hemoglobinuria (dark, tea-colored urine)
• Hemoglobinemia
• Markedly decreased or absent haptoglobin
• Hemosiderinuria (delayed finding)
• More severe acute presentations

Extravascular hemolysis characteristics: 1

• Splenomegaly
• Jaundice without hemoglobinuria
• Moderately decreased haptoglobin
• Spherocytes on peripheral smear
• Generally less acute presentation

Inherited vs. Acquired Classification

Inherited Hemolytic Anemias: 6, 4

Membranopathies:

• Hereditary spherocytosis (most common hereditary hemolytic anemia in Northern Europeans)
• Hereditary elliptocytosis
• Hereditary pyropoikilocytosis
• Southeast Asian ovalocytosis

Enzymopathies:

• G6PD deficiency (most common RBC enzyme defect worldwide)
• Pyruvate kinase deficiency
• Other glycolytic pathway defects

Hemoglobinopathies:

• Sickle cell disease and variants
• Thalassemia syndromes (alpha and beta)
• Unstable hemoglobin variants

Acquired Hemolytic Anemias: 1, 2, 3

Immune-mediated:

• Warm AIHA (IgG-mediated, reacts at 37°C)
• Cold agglutinin disease (IgM-mediated, reacts at <20°C)
• Paroxysmal cold hemoglobinuria (Donath-Landsteiner antibody)
• Drug-induced immune hemolytic anemia
• Alloimmune hemolysis (transfusion reactions, hemolytic disease of the newborn)

Non-immune:

• Microangiopathic hemolytic anemia (hemolytic uremic syndrome, thrombotic thrombocytopenic purpura, disseminated intravascular coagulation)
• Infections (malaria, babesiosis, bartonellosis)
• Mechanical trauma (prosthetic heart valves, march hemoglobinuria)
• Oxidative injury (drugs, chemicals, venoms)
• Hypersplenism
• Paroxysmal nocturnal hemoglobinuria

Detailed Causes & Differentials

Warm Autoimmune Hemolytic Anemia 2, 5, 3

• Primary (50% of cases): Idiopathic with no identifiable underlying condition
• Secondary (50% of cases):
  • Lymphoproliferative disorders (lymphoma, chronic lymphocytic leukemia)
  • Systemic lupus erythematosus
  • Common variable immunodeficiency
  • Autoimmune lymphoproliferative syndrome
  • Post-viral infections (EBV, CMV, HIV)
  • Drug-induced (methyldopa, penicillins, cephalosporins, immune checkpoint inhibitors)

Cold Agglutinin Disease 5, 3

• Primary: Monoclonal IgM production (often associated with lymphoproliferative disorders)
• Secondary:
  • Mycoplasma pneumoniae infection (most common in children)
  • Infectious mononucleosis (EBV)
  • Lymphoma

Paroxysmal Cold Hemoglobinuria 5

• Post-viral infections (most common in children)
• Syphilis (historical, rare in modern practice)
• Characterized by biphasic Donath-Landsteiner antibody

Hereditary Spherocytosis 4

• Defects in RBC membrane proteins (spectrin, ankyrin, band 3, protein 4.2)
• Autosomal dominant inheritance (75% of cases)
• De novo mutations (25% of cases)

G6PD Deficiency 4

• X-linked recessive inheritance
• Over 400 variants identified
• Hemolysis triggered by oxidative stress (infections, fava beans, medications including antimalarials, sulfonamides, nitrofurantoin)

Sickle Cell Disease 4

• Hemoglobin S mutation (glutamic acid to valine substitution at position 6 of beta-globin)
• Autosomal recessive inheritance
• Chronic hemolysis with acute vaso-occlusive crises

Microangiopathic Hemolytic Anemia 1

• Hemolytic uremic syndrome: Often post-diarrheal (Shiga toxin-producing E. coli), presents with triad of hemolytic anemia, thrombocytopenia, and acute kidney injury
• Thrombotic thrombocytopenic purpura: ADAMTS13 deficiency, presents with pentad including fever and neurological symptoms
• Disseminated intravascular coagulation: Consumptive coagulopathy with widespread microvascular thrombosis

Typical Presentations

Acute Presentations 1, 4

• Severe anemia symptoms: Pallor, fatigue, dyspnea, tachycardia, hypotension (in severe cases)
• Jaundice: Scleral icterus, generalized jaundice from unconjugated hyperbilirubinemia
• Dark urine: Hemoglobinuria (intravascular hemolysis) or concentrated urine with urobilinogen
• Abdominal pain: From splenic enlargement or infarction
• Fever: May accompany acute hemolytic episodes, especially in immune-mediated cases

Chronic Presentations 4

• Compensated hemolysis: Mild anemia with reticulocytosis, minimal symptoms
• Growth retardation: In chronic severe hemolysis
• Splenomegaly: Common in extravascular hemolysis
• Gallstones: Pigmented stones from chronic hyperbilirubinemia (can occur in childhood)
• Skeletal changes: Frontal bossing, maxillary hyperplasia in severe chronic hemolysis (thalassemia, sickle cell disease)

Neonatal Presentations 1, 7

• Severe hyperbilirubinemia: Risk of kernicterus if untreated
• Hydrops fetalis: Severe in utero anemia with edema, ascites, pleural effusions
• Hemolytic disease of the fetus and newborn: Maternal alloimmunization (Rh, Kell, other antigens)
• Rapid onset anemia: Within first 24-48 hours of life

Presentation by Specific Etiology

Hereditary spherocytosis: 4

• Neonatal jaundice (50% of cases)
• Intermittent jaundice and anemia
• Splenomegaly
• Positive family history (75%)
• Aplastic crises with parvovirus B19 infection

G6PD deficiency: 4

• Acute hemolytic episodes triggered by oxidative stress
• Neonatal hyperbilirubinemia
• Asymptomatic between episodes
• Male predominance

Warm AIHA: 2, 5

• Insidious onset or acute decompensation
• Pallor and jaundice
• Splenomegaly (variable)
• May have underlying autoimmune or lymphoproliferative symptoms

Cold agglutinin disease: 5

• Acrocyanosis with cold exposure
• Raynaud phenomenon
• Hemolysis exacerbated by cold temperatures
• Often follows Mycoplasma pneumoniae infection in children

Complications

Acute Complications 1, 4

• Severe anemia: Requiring urgent transfusion, risk of high-output cardiac failure
• Hyperbilirubinemia: Risk of kernicterus in neonates
• Acute kidney injury: From hemoglobinuria, hypoperfusion, or associated microangiopathy
• Thrombotic events: Paradoxical thrombosis in severe hemolysis (especially paroxysmal nocturnal hemoglobinuria, sickle cell disease)
• Aplastic crisis: Parvovirus B19 infection causing transient red cell aplasia
• Hemolytic crisis: Acute exacerbation with rapid hemoglobin drop
• Splenic sequestration: Acute splenic enlargement with severe anemia (sickle cell disease)

Chronic Complications 4

• Cholelithiasis: Pigmented gallstones from chronic hyperbilirubinemia
• Iron overload: From chronic transfusions (requires chelation therapy)
• Splenomegaly: With risk of splenic rupture
• Growth retardation: From chronic anemia and increased metabolic demands
• Skeletal abnormalities: Extramedullary hematopoiesis causing bone deformities
• Pulmonary hypertension: From chronic hemolysis (sickle cell disease, thalassemia)
• Leg ulcers: Chronic hemolysis (sickle cell disease)
• Osteoporosis: From bone marrow expansion and endocrine complications

Treatment-Related Complications 3

• Steroid toxicity: Growth suppression, osteoporosis, hypertension, diabetes, infections
• Immunosuppression: Increased infection risk from rituximab, other immunosuppressants
• Splenectomy complications: Overwhelming post-splenectomy infection, thrombosis
• Transfusion complications: Alloimmunization, transfusion reactions, iron overload, infections

Disease-Specific Complications

Sickle cell disease: 4

• Vaso-occlusive crises
• Acute chest syndrome
• Stroke
• Avascular necrosis
• Priapism
• Chronic organ damage (kidneys, heart, lungs)

Thalassemia major: 4

• Transfusion-dependent anemia
• Iron overload with cardiac, hepatic, and endocrine dysfunction
• Osteoporosis
• Extramedullary hematopoiesis

Detailed Approach to History

Present Illness 1, 4

• Onset and duration: Acute (days) vs. chronic (weeks to months)
• Anemia symptoms: Fatigue, weakness, dyspnea on exertion, exercise intolerance, dizziness
• Jaundice: Onset, progression, associated pruritus
• Urine color changes: Dark urine, timing relative to symptom onset
• Abdominal pain: Location, character, associated with meals or activity
• Fever: Pattern, associated symptoms suggesting infection
• Cold exposure: Symptoms triggered or worsened by cold (suggests cold agglutinin disease)
• Recent infections: Respiratory infections (Mycoplasma), gastroenteritis (Shiga toxin E. coli), viral illnesses

Medication and Exposure History 1, 4

• Current medications: Antibiotics (penicillins, cephalosporins, sulfonamides), antimalarials, nitrofurantoin, dapsone
• Recent medication changes: Within past 2-4 weeks
• Herbal supplements: May contain oxidative compounds
• Chemical exposures: Naphthalene (mothballs), aniline dyes
• Dietary exposures: Fava beans (in G6PD deficiency)

Past Medical History 4, 2

• Neonatal jaundice: Severity, treatment required (phototherapy, exchange transfusion)
• Previous anemia: Diagnosed or suspected, treatment received
• Autoimmune conditions: Systemic lupus erythematosus, autoimmune thyroiditis, inflammatory bowel disease
• Immunodeficiency: Recurrent infections, diagnosed immune disorders
• Malignancies: Lymphoma, leukemia
• Previous transfusions: Number, reactions, alloimmunization
• Splenectomy: Timing, indication
• Gallstones: Diagnosed or symptomatic

Family History 4

• Anemia: Affected family members, severity, treatment
• Jaundice: Recurrent or chronic in relatives
• Splenectomy: Family members requiring splenectomy
• Gallstones: Early-onset cholelithiasis in family
• Ethnic background: Mediterranean (thalassemia, G6PD deficiency), African (sickle cell disease, G6PD deficiency), Northern European (hereditary spherocytosis), Southeast Asian (thalassemia, G6PD deficiency)
• Consanguinity: Increases risk of autosomal recessive conditions
• Autoimmune diseases: Family history of lupus, rheumatoid arthritis, other autoimmune conditions

Review of Systems 1, 4

• Constitutional: Fever, weight loss, night sweats (lymphoproliferative disorders)
• Skin: Rash (lupus, drug reactions), leg ulcers (sickle cell disease), acrocyanosis (cold agglutinin disease)
• Cardiovascular: Chest pain, palpitations, syncope
• Respiratory: Dyspnea, cough (acute chest syndrome in sickle cell disease)
• Gastrointestinal: Abdominal pain, diarrhea (hemolytic uremic syndrome), hepatomegaly symptoms
• Genitourinary: Hematuria, dark urine, decreased urine output
• Musculoskeletal: Bone pain (sickle cell crisis), joint pain (autoimmune disease)
• Neurological: Headache, confusion, seizures (thrombotic thrombocytopenic purpura, severe anemia)

Physical Examination

General Appearance 1

• Pallor: Conjunctival, palmar, nail bed pallor indicating anemia severity
• Jaundice: Scleral icterus, generalized jaundice
• Growth parameters: Height, weight, body mass index (chronic hemolysis may cause growth retardation)
• Vital signs: Tachycardia, tachypnea, hypotension (severe anemia), fever

Skin Examination 1, 4

• Pallor: Severity assessment
• Jaundice: Distribution and intensity
• Petechiae or purpura: Suggests thrombocytopenia (microangiopathic hemolytic anemia, Evans syndrome)
• Leg ulcers: Chronic hemolysis (sickle cell disease)
• Acrocyanosis: Cold agglutinin disease
• Rash: Malar rash (lupus), drug eruptions

Head and Neck 4

• Scleral icterus: Unconjugated hyperbilirubinemia
• Frontal bossing: Chronic severe hemolysis with marrow expansion
• Maxillary hyperplasia: Thalassemia major
• Lymphadenopathy: Lymphoproliferative disorders

Cardiovascular 1

• Tachycardia: Compensatory response to anemia
• Flow murmur: Systolic ejection murmur from increased cardiac output
• Gallop rhythm: Congestive heart failure in severe anemia
• Peripheral pulses: Assessment of perfusion

Abdominal Examination 1, 4

• Hepatomegaly: Measure liver span, assess for tenderness
• Splenomegaly: Measure spleen size (cm below left costal margin), assess for tenderness
  • Mild: Palpable 1-4 cm below costal margin
  • Moderate: 4-8 cm below costal margin
  • Massive: >8 cm below costal margin or crossing midline
• Abdominal tenderness: Right upper quadrant (gallstones, hepatomegaly), left upper quadrant (splenic infarction)

Musculoskeletal 4

• Bone tenderness: Sternum, long bones (marrow expansion, sickle cell crisis)
• Joint swelling: Autoimmune disease, sickle cell dactylitis

Neurological 1

• Mental status: Confusion, lethargy (severe anemia, thrombotic thrombocytopenic purpura)
• Focal deficits: Stroke (sickle cell disease, thrombotic thrombocytopenic purpura)
• Cranial nerve examination: Assess for neurological complications

Diagnostic Investigations

Initial Laboratory Tests 1, 4

Complete Blood Count with Differential:

• Hemoglobin/Hematocrit: Degree of anemia
  • Mild: Hb 9-11 g/dL
  • Moderate: Hb 7-9 g/dL
  • Severe: Hb <7 g/dL
• Mean corpuscular volume (MCV): Typically normocytic (80-100 fL) or macrocytic (>100 fL) due to reticulocytosis
• Mean corpuscular hemoglobin concentration (MCHC): Elevated in hereditary spherocytosis (>36 g/dL)
• Red cell distribution width (RDW): Elevated (>15%) indicating anisocytosis
• White blood cell count: May be elevated (stress response) or decreased (autoimmune cytopenias)
• Platelet count: Thrombocytosis (reactive) or thrombocytopenia (Evans syndrome, microangiopathic hemolytic anemia)

Reticulocyte Count: 1, 4

• Absolute reticulocyte count: >100,000/μL indicates bone marrow response
• Reticulocyte percentage: >2% (corrected for hematocrit)
• Corrected reticulocyte count: (Patient Hct/45) × reticulocyte %
• Reticulocyte production index: Corrected count/maturation factor (1.5-2.5 depending on anemia severity)
• Expected finding: Elevated in hemolysis (unless concurrent parvovirus B19 infection or bone marrow suppression)

Peripheral Blood Smear: 1, 4

• Spherocytes: Hereditary spherocytosis, warm AIHA
• Schistocytes (fragmented RBCs): Microangiopathic hemolytic anemia (>1% is significant)
• Bite cells, blister cells: G6PD deficiency during hemolytic episode
• Sickle cells: Sickle cell disease
• Target cells: Thalassemia, hemoglobin C disease, liver disease
• Agglutination: Cold agglutinin disease (may resolve with warming)
• Polychromasia: Reticulocytosis
• Nucleated RBCs: Severe hemolysis, extramedullary hematopoiesis
• Heinz bodies: G6PD deficiency (requires supravital stain)
• Howell-Jolly bodies: Post-splenectomy, functional asplenia

Markers of Hemolysis: 1, 4

• Lactate dehydrogenase (LDH): Elevated (>500 U/L, often >1000 U/L in acute hemolysis)
• Unconjugated (indirect) bilirubin: Elevated (>1.5 mg/dL)
• Haptoglobin: Decreased or undetectable (<25 mg/dL)
  • Most sensitive marker for intravascular hemolysis
  • May be decreased in extravascular hemolysis
• Serum free hemoglobin: Elevated in intravascular hemolysis (>10 mg/dL)
• Urinalysis: Hemoglobinuria (positive blood without RBCs on microscopy), urobilinogen elevation

Immunologic Testing 1, 2, 5

Direct Antiglobulin Test (DAT, Coombs Test):

• Positive with IgG: Warm AIHA
• Positive with C3d: Cold agglutinin disease, paroxysmal cold hemoglobinuria
• Positive with both IgG and C3d: Mixed AIHA, some warm AIHA cases
• Negative DAT: Non-immune hemolysis (hereditary disorders, microangiopathic hemolytic anemia)
  • Note: 5-10% of warm AIHA may have negative DAT (low-affinity antibodies, IgA-mediated)

Indirect Antiglobulin Test (IAT):

• Detects circulating antibodies in serum
• Positive in alloimmunization, some AIHA cases

Cold Agglutinin Titer: 5

• Elevated (>1:64) in cold agglutinin disease
• Thermal amplitude testing (reactivity at 30-37°C correlates with clinical severity)

Donath-Landsteiner Test: 5

• Positive in paroxysmal cold hemoglobinuria
• Biphasic hemolysin: binds at cold temperature, causes hemolysis upon rewarming

Specific Tests for Hereditary Hemolytic Anemias 4

Osmotic Fragility Test:

• Increased fragility in hereditary spherocytosis
• Incubated osmotic fragility more sensitive than fresh
• Abnormal result: Hemolysis at NaCl concentrations >0.5%

Eosin-5-Maleimide (EMA) Binding Test:

• Flow cytometry-based test for hereditary spherocytosis
• More sensitive and specific than osmotic fragility
• Decreased fluorescence indicates membrane protein deficiency

G6PD Enzyme Activity:

• Quantitative assay measuring enzyme activity
• Deficient: <10% of normal activity (severe variants)
• Intermediate: 10-60% of normal (moderate variants)
• Caution: May be falsely normal during acute hemolysis (young RBCs have higher enzyme activity); retest 2-3 months after hemolytic episode

Hemoglobin Electrophoresis: 4

• Sickle cell disease: Hemoglobin S predominates (>50%), variable HbF
• Sickle cell trait: HbA >HbS
• Beta-thalassemia major: Elevated HbF (>70%), absent or reduced HbA
• Beta-thalassemia minor: Elevated HbA2 (>3.5%)
• Hemoglobin C disease: HbC present

High-Performance Liquid Chromatography (HPLC):

• Quantifies hemoglobin variants
• More precise than electrophoresis for HbA2 measurement

Pyruvate Kinase Activity:

• Enzyme assay for pyruvate kinase deficiency
• Deficient: <50% of normal activity

Advanced/Specialized Testing 4, 5

Flow Cytometry:

• CD55 and CD59 expression for paroxysmal nocturnal hemoglobinuria
• EMA binding for hereditary spherocytosis
• Lymphocyte subsets in immunodeficiency-associated AIHA

Genetic Testing:

• Membrane protein gene sequencing (hereditary spherocytosis)
• G6PD gene sequencing (when enzyme assay equivocal)
• Hemoglobin gene sequencing (atypical hemoglobinopathies)
• Next-generation sequencing panels for undiagnosed hemolytic anemias

Bone Marrow Examination:

• Indications: Atypical presentation, suspected bone marrow disorder, reticulocytopenia
• Expected findings in hemolysis: Erythroid hyperplasia, increased myeloid:erythroid ratio reversal (normally 3:1, becomes 1:1 or lower)
• Abnormal findings: Dysplasia (myelodysplastic syndrome), infiltration (leukemia, lymphoma), aplasia (aplastic crisis)

Autoimmune Workup (for AIHA): 2, 5

• Antinuclear antibody (ANA)
• Anti-double-stranded DNA
• Complement levels (C3, C4)
• Immunoglobulin levels
• Lymphocyte subsets
• HIV testing

Infectious Workup: 1

• Mycoplasma pneumoniae serology and PCR
• Epstein-Barr virus serology
• Cytomegalovirus serology
• Parvovirus B19 PCR (if reticulocytopenia)
• Malaria smear (if travel history)

Imaging Studies 4

Abdominal Ultrasound:

• Assess spleen size (normal: <12 cm in adolescents)
• Evaluate for gallstones
• Assess liver size and echogenicity

Transcranial Doppler (Sickle Cell Disease):

• Screen for stroke risk
• Elevated velocities (>200 cm/sec) indicate high risk

Diagnostic Criteria

Hemolytic Anemia Diagnosis 1, 4

Definitive diagnosis requires:

1. Anemia: Hemoglobin below age-appropriate normal
2. Evidence of increased RBC destruction:
   • Elevated LDH (>500 U/L)
   • Elevated unconjugated bilirubin (>1.5 mg/dL)
   • Decreased haptoglobin (<25 mg/dL)
3. Evidence of bone marrow response:
   • Reticulocytosis (corrected reticulocyte count >2%)
   • Polychromasia on peripheral smear

Warm AIHA Diagnostic Criteria 2, 5

1. Evidence of hemolytic anemia (as above)
2. Positive DAT with IgG (with or without C3d)
3. Antibody reactivity at 37°C
4. Exclusion of drug-induced hemolysis

Cold Agglutinin Disease Diagnostic Criteria 5

1. Evidence of hemolytic anemia
2. Positive DAT with C3d (IgG typically negative)
3. Elevated cold agglutinin titer (>1:64)
4. Thermal amplitude extending to ≥30°C
5. Symptoms exacerbated by cold exposure

Paroxysmal Cold Hemoglobinuria Diagnostic Criteria 5

1. Evidence of hemolytic anemia
2. Positive Donath-Landsteiner test
3. Positive DAT with C3d during hemolytic episode
4. Hemoglobinuria
5. Often post-viral illness in children

Hereditary Spherocytosis Diagnostic Criteria 4

Definitive diagnosis requires 3 of 4:

1. Family history of hereditary spherocytosis
2. Spherocytes on peripheral smear
3. Negative DAT
4. Abnormal osmotic fragility or EMA binding test

Supportive findings:

• Elevated MCHC (>36 g/dL)
• Splenomegaly
• Intermittent jaundice

G6PD Deficiency Diagnostic Criteria 4

1. Acute hemolytic episode triggered by oxidative stress
2. Bite cells or blister cells on peripheral smear during hemolysis
3. G6PD enzyme activity <60% of normal (test 2-3 months after acute episode)
4. Male gender or family history (X-linked inheritance)

Microangiopathic Hemolytic Anemia Diagnostic Criteria 1

1. Evidence of hemolytic anemia
2. Schistocytes >1% on peripheral smear
3. Thrombocytopenia
4. Negative DAT
5. Evidence of underlying condition (hemolytic uremic syndrome, thrombotic thrombocytopenic purpura, disseminated intravascular coagulation)

Initial Management

Acute Stabilization 1, 3

Assess Severity and Stabilize:

• Hemoglobin <7 g/dL or symptomatic anemia: Consider urgent transfusion
• Hemodynamic instability: Intravenous fluid resuscitation, oxygen supplementation
• Severe hemolysis with hemoglobinuria: Aggressive hydration to prevent acute kidney injury (1.5-2 times maintenance fluids)

Red Blood Cell Transfusion: 1

• Indications:
  • Hemoglobin <7 g/dL with symptoms
  • Hemoglobin <5 g/dL regardless of symptoms
  • Hemodynamic instability
  • Acute chest syndrome (sickle cell disease)
  • Stroke (sickle cell disease)
• Dose: 10-15 mL/kg of packed RBCs (raises hemoglobin by approximately 2-3 g/dL)
• Rate: Transfuse over 2-4 hours (slower if concern for volume overload)
• Special considerations:
  • Use leukoreduced, cross-matched blood
  • In AIHA, use least incompatible units if no compatible blood available
  • Warm blood to 37°C in cold agglutinin disease
  • Extended phenotype matching in sickle cell disease to prevent alloimmunization
  • Avoid transfusion in hemolytic uremic syndrome unless life-threatening anemia (may worsen thrombotic microangiopathy)

Folic Acid Supplementation: 4

• Dose: 1 mg PO daily for children <1 year; 5 mg PO daily for children ≥1 year
• Indication: All patients with chronic hemolysis to prevent megaloblastic anemia from folate depletion

Management by Etiology

Warm AIHA Initial Management 2, 5, 3

First-Line Therapy: Corticosteroids

• Prednisone: 2-4 mg/kg/day PO (maximum 60-80 mg/day) divided twice daily
  • Continue until hemoglobin stabilizes (typically 2-4 weeks)
  • Taper gradually over 2-3 months once hemoglobin >10 g/dL and reticulocyte count normalizing
• Methylprednisolone: 1-2 mg/kg/day IV divided every 6-12 hours for severe cases
  • Use IV route if unable to tolerate oral, severe hemolysis, or hemodynamic instability

Intravenous Immunoglobulin (IVIG):

• Dose: 1 g/kg/day IV for 1-2 days (maximum 2 g/kg total dose)
• Indications:
  • Severe life-threatening hemolysis
  • Adjunct to corticosteroids in acute presentation
  • Rapid response needed (works within 24-72 hours)
• Infusion rate: Start at 0.5 mL/kg/hour, increase gradually to maximum 4 mL/kg/hour as tolerated

Supportive Care:

• Folic acid 5 mg PO daily
• Prophylactic anticoagulation if severe hemolysis (LDH >1000 U/L): Enoxaparin 0.5 mg/kg subcutaneously every 12 hours
• Avoid cold exposure
• Transfusion as indicated (see above)

Severe/Refractory Cases (Adjunct to Steroids):

• Plasma exchange: 1-1.5 plasma volumes daily for 3-5 days in life-threatening hemolysis
• High-dose methylprednisolone: 10-30 mg/kg/day IV (maximum 1 g/day) for 3 days

Cold Agglutinin Disease Initial Management 5, 3

Avoid Cold Exposure:

• Maintain warm environment
• Warm intravenous fluids and blood products to 37°C
• Use blood warmers for transfusions

Corticosteroids:

• Less effective than in warm AIHA
• Prednisone 1-2 mg/kg/day PO may provide modest benefit
• Consider in acute exacerbations

Rituximab (for severe cases):

• Dose: 375 mg/m² IV weekly for 4 weeks
• More effective than steroids in cold agglutinin disease
• Premedicate with acetaminophen 15 mg/kg PO and diphenhydramine 1 mg/kg IV (maximum 50 mg)

Supportive Care:

• Folic acid 5 mg PO daily
• Transfusion with blood warmer as needed
• Treat underlying infection (Mycoplasma pneumoniae: azithromycin 10 mg/kg PO day 1, then 5 mg/kg PO daily for 4 days)

Paroxysmal Cold Hemoglobinuria Management 5

Supportive Care:

• Avoid cold exposure
• Warm environment
• Transfusion support as needed (use blood warmer)
• Folic acid 5 mg PO daily

Corticosteroids (if severe):

• Prednisone 2 mg/kg/day PO
• Usually self-limited; steroids may shorten duration

IVIG (if severe):

• 1 g/kg/day IV for 1-2 days

Hereditary Spherocytosis Management 4

Acute Hemolytic Crisis:

• Supportive care with transfusion if symptomatic
• Folic acid 5 mg PO daily (lifelong)
• Treat precipitating infections

Aplastic Crisis (Parvovirus B19):

• Transfusion support (may require multiple transfusions over 1-2 weeks)
• IVIG 1 g/kg IV if immunocompromised
• Spontaneous recovery expected in 7-10 days

Definitive Treatment:

• Splenectomy: Curative for anemia (not for underlying membrane defect)
  • Indications: Severe anemia requiring frequent transfusions, symptomatic anemia affecting quality of life, growth retardation
  • Timing: Defer until age ≥6 years if possible (preferably after age 8-10 years) to reduce infection risk
  • Pre-splenectomy vaccinations (2-4 weeks before surgery):
    • Pneumococcal conjugate vaccine (PCV13)
    • Pneumococcal polysaccharide vaccine (PPSV23)
    • Meningococcal conjugate vaccine (MenACWY)
    • Meningococcal B vaccine (MenB)
    • Haemophilus influenzae type b vaccine (Hib)
  • Post-splenectomy prophylaxis:
    • Penicillin V 125 mg PO twice daily (age <5 years) or 250 mg PO twice daily (age ≥5 years) lifelong
    • Alternative: Amoxicillin 20 mg/kg PO once daily (maximum 250 mg)
    • Erythromycin 250 mg PO twice daily if penicillin-allergic

Partial Splenectomy:

• Consider in young children to preserve some splenic function
• Removes 80-90% of spleen

G6PD Deficiency Management 4

Acute Hemolytic Episode:

• Discontinue offending agent (medication, fava beans, other oxidative stressor)
• Hydration: 1.5-2 times maintenance IV fluids to prevent acute kidney injury
• Transfusion if hemoglobin <7 g/dL or symptomatic
• Folic acid 5 mg PO daily during acute episode

Prevention:

• Avoid known triggers:
  • Medications: Primaquine, dapsone, nitrofurantoin, sulfonamides, rasburicase, methylene blue
  • Foods: Fava beans
  • Infections: Prompt treatment
• Provide written list of medications to avoid
• Medical alert bracelet

Neonatal Hyperbilirubinemia:

• Phototherapy per standard guidelines
• Exchange transfusion if severe (total bilirubin >20-25 mg/dL or signs of kernicterus)

Sickle Cell Disease Management 4

Acute Hemolytic Crisis:

• Hydration: 1.5 times maintenance IV fluids
• Oxygen if hypoxic (SpO2 <95%)
• Pain management: Opioids as needed
• Transfusion if hemoglobin drops >2 g/dL below baseline or <5 g/dL

Acute Chest Syndrome:

• Oxygen supplementation
• Incentive spirometry
• Antibiotics: Ceftriaxone 50-75 mg/kg IV daily (maximum 2 g) plus azithromycin 10 mg/kg PO day 1, then 5 mg/kg daily
• Simple transfusion or exchange transfusion (target hemoglobin 10 g/dL, HbS <30%)

Stroke:

• Emergency exchange transfusion: Target HbS <30%, hemoglobin 10 g/dL
• Neurology consultation
• Chronic transfusion program

Chronic Management:

• Hydroxyurea: 15-20 mg/kg PO daily, increase by 5 mg/kg every 8 weeks to maximum 35 mg/kg/day (monitor CBC every 2-4 weeks)
• Folic acid 1 mg PO daily
• Penicillin prophylaxis: Penicillin V 125 mg PO twice daily (age <3 years), 250 mg PO twice daily (age ≥3 years) until at least age 5 years
• Vaccinations: Pneumococcal, meningococcal, Haemophilus influenzae type b, annual influenza
• Transcranial Doppler screening annually starting age 2 years

Microangiopathic Hemolytic Anemia Management 1

Hemolytic Uremic Syndrome:

• Supportive care: Mainstay of treatment
• Fluid and electrolyte management
• Blood pressure control
• Transfusion for symptomatic anemia (hemoglobin <7 g/dL)
• Avoid: Antibiotics (if Shiga toxin-associated), antimotility agents, platelet transfusions (unless active bleeding)
• Dialysis if indicated (severe acute kidney injury, hyperkalemia, volume overload)
• Eculizumab 600-900 mg IV weekly (for atypical hemolytic uremic syndrome with complement dysregulation)

Thrombotic Thrombocytopenic Purpura:

• Plasma exchange: 1-1.5 plasma volumes daily until platelet count >150,000/μL for 2 consecutive days
• Corticosteroids: Methylprednisolone 1-2 mg/kg/day IV
• Rituximab 375 mg/m² IV weekly for 4 weeks (if refractory or relapsing)
• Caplacizumab 10 mg IV loading dose, then 10 mg subcutaneously daily (if available, for acquired thrombotic thrombocytopenic purpura)
• Avoid: Platelet transfusions (may worsen thrombosis)

Ongoing Management

Monitoring During Treatment 3

Warm AIHA on Corticosteroids:

• CBC with reticulocyte count: Weekly until stable, then every 2-4 weeks during taper
• LDH, bilirubin, haptoglobin: Every 1-2 weeks initially, then monthly
• DAT: Repeat at 3-6 months (may remain positive despite clinical remission)
• Steroid side effects monitoring:
  • Blood pressure: Every visit
  • Growth parameters: Monthly
  • Glucose: Monthly if on high-dose or prolonged therapy
  • Bone density: If prolonged therapy (>3 months)
  • Ophthalmology: Every 6-12 months (cataracts, glaucoma)

Chronic Hemolytic Anemias:

• CBC: Every 3-6 months
• Reticulocyte count: Every 3-6 months
• LDH, bilirubin: Every 6-12 months
• Abdominal ultrasound: Annually (assess spleen size, screen for gallstones)
• Growth and development: Every 6 months

Second-Line Therapy for Refractory Warm AIHA 3

Rituximab (Preferred Second-Line):

• Dose: 375 mg/m² IV weekly for 4 weeks
• Alternative dosing: 100 mg/m² IV weekly for 4 weeks (lower dose may be effective with fewer side effects)
• Premedication: Acetaminophen 15 mg/kg PO and diphenhydramine 1 mg/kg IV (maximum 50 mg)
• Response: Expected in 4-8 weeks, duration 1-2 years
• Monitoring: CBC weekly during treatment, then monthly; immunoglobulin levels every 3-6 months
• Advantages: Avoids long-term steroid toxicity, effective in 60-80% of pediatric cases

Splenectomy (Traditional Second-Line):

• Indications: Steroid-dependent (unable to taper below 0.3 mg/kg/day), steroid-refractory, rituximab failure
• Timing: Defer until age ≥6 years if possible
• Pre-operative preparation: Same as hereditary spherocytosis (see above)
• Response rate: 60-70% achieve complete remission
• Risks: Overwhelming post-splenectomy infection (1-2% lifetime risk), thrombosis

Third-Line and Refractory AIHA Management 3

Immunosuppressive Agents:

• Mycophenolate mofetil: 600 mg/m² PO twice daily (maximum 1 g twice daily)
  • Monitor CBC, liver function tests monthly
• Azathioprine: 2-3 mg/kg PO daily (maximum 150 mg)
  • Check thiopurine methyltransferase (TPMT) activity before starting
  • Monitor CBC, liver function tests monthly
• Cyclosporine: 3-5 mg/kg/day PO divided twice daily
  • Monitor trough levels (target 100-200 ng/mL), creatinine, blood pressure

Novel Agents (for Severe Refractory Cases):

• Fostamatinib: Spleen tyrosine kinase inhibitor, 150 mg PO twice daily (limited pediatric data)
• Daratumumab: Anti-CD38 monoclonal antibody, 16 mg/kg IV weekly for 8 weeks (case reports in children)
• Bortezomib: Proteasome inhibitor targeting plasma cells, 1.3 mg/m² IV twice weekly (case reports)

Management of Relapse 3

Warm AIHA Relapse:

• First relapse:
  • Reinitiate prednisone 2 mg/kg/day PO
  • Consider rituximab if steroid-dependent or multiple relapses
• Multiple relapses:
  • Rituximab 375 mg/m² IV weekly for 4 weeks
  • If rituximab failure: Consider splenectomy or third-line immunosuppression
• Maintenance therapy: Not routinely recommended; treat relapses as they occur

Cold Agglutinin Disease Relapse:

• Avoid cold exposure
• Rituximab 375 mg/m² IV weekly for 4 weeks (more effective than steroids)
• Consider rituximab plus bendamustine in severe refractory cases (limited pediatric data)

Management of Complications

Aplastic Crisis (Parvovirus B19): 4

• Transfusion support (may require multiple transfusions over 1-2 weeks)
• IVIG 1 g/kg IV if immunocompromised or severe anemia
• Isolation precautions (droplet)
• Spontaneous recovery expected in 7-10 days

Hyperbilirubinemia and Gallstones: 4

• Ursodeoxycholic acid 10-15 mg/kg/day PO divided twice daily (may prevent gallstone formation)
• Cholecystectomy if symptomatic cholelithiasis (can be performed laparoscopically at time of splenectomy)

Iron Overload (Transfusion-Dependent): 4

• Monitor: Serum ferritin every 3 months, liver MRI T2* annually
• Chelation therapy indications: Ferritin >1000 ng/mL or >20 transfusions
• Deferasirox: 20-30 mg/kg PO daily (dispersible tablet or granules)
• Deferoxamine: 20-40 mg/kg subcutaneously over 8-12 hours, 5-7 nights per week
• Deferiprone: 75-100 mg/kg/day PO divided three times daily

Thrombosis (Severe Hemolysis): 3

• Prophylactic anticoagulation: Enoxaparin 0.5 mg/kg subcutaneously every 12 hours if LDH >1000 U/L
• Therapeutic anticoagulation if thrombosis occurs: Enoxaparin 1 mg/kg subcutaneously every 12 hours

Infection Prevention Post-Splenectomy: 4

• Penicillin prophylaxis: Penicillin V 125 mg PO twice daily (age <5 years) or 250 mg PO twice daily (age ≥5 years) lifelong
• Vaccinations: Pneumococcal (PCV13, PPSV23), meningococcal (MenACWY, MenB), Haemophilus influenzae type b, annual influenza
• Prompt evaluation and treatment of fever (temperature ≥38.5°C): Blood cultures, empiric antibiotics (ceftriaxone 50 mg/kg IV, maximum 2 g)

Prognosis and Follow-Up

Warm AIHA Prognosis 2, 3

• Primary warm AIHA: 60-80% achieve remission with first-line therapy
• Relapse rate: 50-60% within 2 years
• Mortality: <5% in children (lower than adults)
• Chronic/relapsing course: 30-40% require long-term immunosuppression
• Secondary warm AIHA: Prognosis depends on underlying condition

Cold Agglutinin Disease Prognosis 5

• Post-infectious (Mycoplasma): Excellent prognosis, usually self-limited (resolves in 2-6 weeks)
• Primary/chronic: May require ongoing therapy, rituximab effective in 50-60%
• Mortality: Rare in children

Paroxysmal Cold Hemoglobinuria Prognosis 5

• Excellent prognosis: Usually self-limited, resolves in 1-2 weeks
• Recurrence: Rare
• Mortality: <1%

Hereditary Spherocytosis Prognosis 4

• Mild disease (compensated hemolysis): Normal lifespan, may not require splenectomy
• Moderate to severe disease: Excellent prognosis after splenectomy (anemia resolves, though spherocytes persist)
• Post-splenectomy: Lifelong risk of overwhelming infection (1-2% lifetime risk)
• Gallstones: 50% develop by age 30 years if not splenectomized

G6PD Deficiency Prognosis 4

• Excellent prognosis: Normal lifespan if triggers avoided
• Hemolytic episodes: Self-limited, resolve in 1-2 weeks after trigger removal
• Neonatal hyperbilirubinemia: Risk of kernicterus if untreated, otherwise excellent outcome

Sickle Cell Disease Prognosis 4

• Median survival: 40-50 years (improving with modern therapy)
• Hydroxyurea: Reduces vaso-occlusive crises by 50%, improves survival
• Chronic transfusion: Prevents stroke recurrence in 90%
• Hematopoietic stem cell transplantation: Curative, 90-95% disease-free survival (limited by donor availability)
• Gene therapy: Emerging curative option

Microangiopathic Hemolytic Anemia Prognosis 1

• Typical hemolytic uremic syndrome (Shiga toxin): 90-95% recovery, 5-10% develop chronic kidney disease
• Atypical hemolytic uremic syndrome: 50% mortality or end-stage renal disease without eculizumab; with eculizumab, 80-90% renal recovery
• Thrombotic thrombocytopenic purpura: 80-90% survival with plasma exchange, 30-40% relapse rate

Follow-Up Recommendations

Warm AIHA: 3

• During active treatment: Weekly CBC until stable, then every 2-4 weeks during steroid taper
• After remission: Every 3-6 months for 2 years, then annually
• Monitor for: Relapse (anemia, jaundice, dark urine), steroid side effects, underlying conditions

Hereditary Spherocytosis: 4

• Pre-splenectomy: Every 6-12 months (CBC, reticulocyte count, bilirubin, abdominal ultrasound)
• Post-splenectomy: Annually (CBC, vaccination status, infection history)
• Lifelong: Monitor for gallstones, ensure compliance with antibiotic prophylaxis

G6PD Deficiency: 4

• After diagnosis: Provide trigger avoidance education, medical alert bracelet
• Routine follow-up: Not required unless recurrent hemolysis
• Neonatal hyperbilirubinemia: Close monitoring in first week of life

Sickle Cell Disease: 4

• Comprehensive care: Every 3-6 months at specialized center
• Monitoring: CBC, reticulocyte count, liver function tests, renal function, transcranial Doppler (annually age 2-16 years)
• Hydroxyurea: CBC every 2-4 weeks initially, then every 2-3 months
• Chronic transfusion: Every 3-4 weeks, monitor for iron overload (ferritin every 3 months)

Microangiopathic Hemolytic Anemia: 1

• Hemolytic uremic syndrome: Weekly during acute phase, then every 3-6 months for 1 year (monitor renal function, blood pressure, proteinuria)
• Thrombotic thrombocytopenic purpura: Weekly during treatment, then monthly for 6 months, then every 3 months (monitor for relapse)