HAEMOLYTIC ANAEMIAThe nuts & bolts

RBCs – A History• Anucleate cell

• Anaerobic glycolysis – No backup

• Lifespan = 120 days

Anaemia – WHY?• DECREASED production

• DECREASED lifespan (increased destruction)

• INCREASED loss

• DECREASED lifespan = HAEMOLYTIC ANAEMIA

ClassificationIntracorpuscular Defects

Extracorpuscular Factors

Hereditary • Hemoglobinopathies

• Enzymopathies

• Membrane-cytoskeletal defects

• Familial (atypical) hemolytic uremic syndrome

Acquired • Paroxysmal nocturnal hemoglobinuria (PNH)

• Mechanical destruction (microangiopathic)

• Toxic agents• Drugs• Infectious• Autoimmune

Clinically• Onset –

• Acute• Chronic

• Site –• Intravascular• Extravascular

Symptoms• Jaundice

• Yellowish urine

• Reddish urine

• Skeletal abnormalities (marrow overactivity)

Signs• Jaundice

• Pallor

• Splenomegaly

• Hepatomegaly

Labs• Increase in –

• Unconjugated bilirubin• Aspartate transaminase (AST/SGOT)• Urobilinogen (in both urine and stool)

• Mainly intravascular –• ↑ Lactate dehydrogenase (LDH)• ↑ Serum hemoglobin (free Hb)• Hemoglobinuria• Hemosiderinuria• ↓ Haptoglobin • Bilirubin level – normal/mildly ↑

Labs II• Increase in reticulocytes –

• Percentage of reticulocytes• Absolute reticulocyte count

• MCV increased

• Peripheral smear –• Macrocytes• Polychromasia• Nucleated RBCs

INHERITED DEFECTS

CYTOSKELETON DEFECTS• Main proteins-

• Glycophorins• Ankyrin• Spectrin

• Major defects-• Hereditary spherocytosis• Hereditary elliptocytosis

Hereditary Spherocytosis• Heterogeneous group• Ankyrin, Spectrin• Classic AD – Family history positive• Rare AR – severe disease• Presentation-

• Varies broadly• Severe – infancy• Mild – Adulthood/ incidental in pregnancy

• Clinical-• Jaundice• Splenomegaly• Gallstones – suspicious in young

Hereditary Spherocytosis (contd)• Labs-

• Normocytic, Spherocytes• MCHC ↑• Osmotic fragility ↑• Molecular studies – mutation

• Management-• Supportive• Splenectomy• Cholecystectomy

Hereditary Elliptocytosis• Heterogeneous group

• Elliptocytes

• Similar to spherocytosis in-• Presentation• Clinical features• Management

CATION TRANSPORT DEFECTS• VERY rare• Autosomal dominant• Intracell Na+ ↑• Intracell K+ ↓• Pseudohyperkalemia• RBC swells – somatocytes• RBC shrinks – xerocytes• No specific Rx• Splenectomy CONTRAINDICATED

ENZYME DEFECTS• Redox OR Glycolytic

• Commonest-• G6PD• Pyruvate Kinase• Glucose Phosphatase Isomerase

G6PD Deficiency• X-linked

• Males +/-

• Females – genetic mosaic

• ↓ In-vivo stability of protein

• Denaturation of Hb

G6PD Deficiency (contd)• Asymptomatic

• Precipitated by oxidative stress-• Infections• Drugs• Fava beans (അമരക്ക)

• Neonatal-• Jaundice• Kernicterus – neurologic damage

G6PD Deficiency (contd)• Gradual/abrupt

• Initial-• Malaise• Weakness• Abdominal/limb pain

• Later-• Jaundice• Dark coloured urine

G6PD Deficiency (contd)• Primaquine• Chloroquine• Chlorproguanil• Sulfamethoxazole• Dapsone• Cotrimoxazole• Nalidixic acid• Nitrofurantoin• Niridazole• Acetanilide• Phenazopyridine• Naphthalene• Methylene blue

G6PD Deficiency (contd)• Anaemia – moderate to severe

• Peripheral smear –• Normocytic and chromic• Anisocytocis/Poikilocytosis/Spherocytosis/Bite cells• Polychromasia• HEINZ BODIES (denatured Hb)

• Quantitative G6PD assay (activity)

G6PD Deficiency (contd)• Avoid precipitants

• Rx acute events promptly – • Blood transfusion• Haemodialysis• Hydration

• Full recovery usual

• Complication – Renal failure

Pyruvate Kinase Deficiency• Rare

• Clinical –• Neonatal jaundice• High reticulocyte count• Variable severity

• Rx – • Supportive

• Oral folic acid• Blood transfusions• Chelate iron overload

• Severe - Splenectomy

HAEMOGLOBINOPATHIES• Types-

• Qualitative• Quantitative

• Haemoglobin-• Fetal – αα/γγ• Adult – αα/ββ

HAEMOGLOBINOPATHIES (contd)• Qualitative-

• Hundreds of variants• Sickle cell anaemia – HbS

• Quantitative-• Reduced globin chain production• Alpha thalassemia – no/reduced Alpha globins• Beta thalassemia – Minor/Major

HbS• Beta globin chain• Position 6• Glutamic acid → Valine• Trait – one allele (AS)• Disease – both alleles (SS)

• Pathogenesis-• Deoxygenation = HbS polymerisation• Sickle shaped pseudocrystals = Tactoids• HbS reverses, RBC membrane does not• Other variant Hb can ↑/↓ polymerisation

HbS (contd)• Crises & Chronic organ damage• Precipitated by-

• Hypoxia• Acidosis• Dehydration• Infection

• Pathophysiology-• Sickle cell life ↓• Plug microvasculature

HbS Crises• Vaso-occlusive-

• Most common of crises• Acute severe bone pain• Dactylitis, femora, humeri, ribs, pelvis, vertebrae• Tachycardia, sweating, fever

• Sickle chest-• MC cause of death in adult HbS• BM infarction = fat embolism to lungs• Ventilatory failure

HbS Crises (contd)• Sequestration-

• Venous occlusion• Massive splenomegaly• Hepatomegaly• Severe anaemia, circulatory collapse

• Aplastic-• Human erythrovirus 19 infection• Severe, self-limiting red cell aplasia

HbS (contd)• Labs-

• Compensated anemia• Sickle cells, target cells• Reticulocytosis• Hyposplenism• Sickling test – Sodium dithionite• Hb electrophoresis

HbS Management• Supportive-

• Folic acid• Penicillin V• Pneumococcal, Haemophilus influenzae B, Hep B vaccination

• Crises-• Aggressive hydration• Oxygen therapy• Analgesia – Opiates• Antibiotics• Regular transfusion – recurrent crises• Exchange transfusion – prep for Sx/life threatening crises

• Hydroxycarbamide- more HbF• Allogenic BM transplant

β-Thalassemia• More common of thalassemias• Heterozygotes-

• Thalassemia minor• Incidental detection – iron therapy fails• Asymptomatic• Mild anaemia• Microcytic hypochromic erythrocytes (not iron-deficient)• Some target cells• Punctate basophilia• Raised haemoglobin A2 fraction• Evidence that one parent has thalassaemia minor

β-Thalassemia (contd)• Homozygotes-

• Thalassemia major• First 4-6 months of life• Profound hypochromic anaemia• Evidence of severe red cell dysplasia• Erythroblastosis• Absence or gross reduction of the amount of haemoglobin A• Raised levels of haemoglobin F• Evidence that both parents have thalassaemia minor

β-Thalassemia (contd)

α-Thalassemia• 2 loci, 2 chromosomes = 4 alleles

• 1 deleted = asymptomatic• 2 deleted = mild hypochromic anaemia• 3 deleted = HbH disease (nonfunctional, chronic hypoxia)• 4 deleted = Hydrops fetalis

• Rx-• Similar to moderate beta thal• Folic acid, blood transfusion• Avoid iron therapy

FAMILIAL ATYPICAL HUS (FaHUS)• Atypical = NO E.coli / Shiga toxin• Mutations – complement regulatory protein genes• Extracorpuscular defect

• Clinical –• Microangiopathic HA• Fragmented RBCs in PS• Mild thrombocytopenia• Acute renal failure

• ESRD = in 50% (severe disease)

ACQUIRED DEFECTS

MECHANICAL• March haemoglobinuria-

• Acute, self inflicted• Marathon runners, Long marchers

• Microangiopathic haemolytic anaemia-• Chronic, iatrogenic• Prosthetic heart valves• Mild – no Rx• More severe – correct regurgitation

TOXINS & DRUGS• Hapten-like action (Penicillins)

• Mimicry –• Ab against RBC Ag• Methyldopa

• Direct chemical action –• Oxidative – Hyperbaric O2, nitrates, cisplatin, dapsone• Unknown mech - Copper, lead• Direct RBC lysis – Snake & spider venom (enzymes)

INFECTIONS• Malaria

• Haemolytic uraemic syndrome –• E. coli• Shiga toxin

• Clostridium perfringens sepsis

• Sepsis

• Endocarditis

AUTOIMMUNE HA• Second most common acquired HA

• Autoantibody to RBC Ag-• Phagocytosis – extravascular• Complement – intravascular

• Clinical-• Jaundice, splenomegaly, Hburia• Abrupt Hb ↓• Coombs test positive• Assoc – general autoimmune disease (SLE)• Autoimmune thrombocytopenia – Evans syndrome

AUTOIMMUNE HA (contd)• Medical emergency

• Blood transfusion• Steroids – prednisone• Rituximab – anti CD20• Azathioprine, cyclosporine, cyclophosphamide, IVIg• Splenectomy• Stem cell transplantation

AUTOIMMUNE HA variants• Paroxysmal cold Hburia

• Rare, Self-limiting• Viral trigger, Donath-Landsteiner Ab, Anti-P• Attach @ 4 ͦ°C, Complement activated @ 37°C• Supportive Rx, transfusion

• Cold agglutinin disease• Ab react at cold temp• Anti-I IgM• Related to Waldenstroms macroglobulinemia• Rituximab• Avoid cold exposure

PAROXYSMAL NOCTURNAL HbURIA

• Acquired chronic HA• Persistent intravascular haemolysis• Recurrent exacerbations

• Triad-• Intravascular haemolysis• Venous thrombosis• Pancytopenia

• Pathophysiology-• Absent CD59 & CD55• Extremely sensitive to complement C

PNH (contd)• Classic – Passed blood, not urine, in the morning

• Workup of-• Anemia• Cytopenias• Pancytopenia• Recurrent severe abdominal pain• Budd-Chiari syndrome

• Past h/o OR evolve into Aplastic anaemia

• AML also endpoint

PNH (contd)• Lab-

• Anaemia – normo/macro• Cytopenia – Pan/mono• Uncojugated bilirubin ↑• LDH ↑↑↑• Haptoglobulin undetectable• Haemoglobinuria• Flow cytometry – Absent CD59 & CD55• Marrow – Cellular/Hypo/Aplastic

PNH (contd)• Eculizumab-

• Humanized monoclonal antibody• Against Complement component C5

• Supportive-• Folic acid• Iron supplements

• Anticoagulant prophylaxis

• Allogenic bone marrow transplant