Haemolytic Anaemia

Question 1

Anaemia vs haemolytic anaemia

Answer 1

Anemia = ↓ Hb for age/gender
HA = anaemia due to ↓ RBC survival

Question 2

RBC life cycle - brief

Answer 2

RBC prod needs = iron, B12, folate, globin chains, protoporphyrins (carry heme),

loose nucleus on the way out from BM – into circulation live for 120 days​

changes on CM identified by macrophages in liver and spleen which remove those RBCs

Question 3

Mature RBC - metabolic pathways

Answer 3

Glycolytic pathway, hexose monophosphate shunt

Question 4

Haemolysis - effect

Answer 4

Haemolysis = shortened RBC survival,

BM compensates w/increased RBC production

= ↑ young cells in circulation

= reticulocytosis +/- nucleated RBC

Question 5

What is compensated haemolysis

Answer 5

RBC production able to compensate for decreased RBC life span = normal Hb​

Question 6

What is incompletely compensated haemolysis

Answer 6

RBC production unable to keep up with decreased RBC life span = decreased Hb ​ ​

Question 7

Clinical findings of haemolytic anaemia

Answer 7

Jaundice = unconjugated bilirubin ​
Pallor/fatigue​
Splenomegaly, increased bilirubin ​
Dark urine

Question 8

Haemolytic crisis - define

Answer 8

Increased anaemia and jaundice with infections/precipitants​

Question 9

Aplastic crisis - define

Answer 9

Anaemia, reticulocytopenia with parvovirus infection = rash/red cheeks, infects BM

Question 10

Chronica haemolytic anaemia - clinical findings

Answer 10

Gallstones – pigment​
Splenomegaly ​
Leg ulcers - free Hb scavenges NO   ​
Folate deficiency ​
(increased use) = acute hemolysis = more folate to make more RBCs

Question 11

Haemolytic anaemia laboratory findings

Answer 11

Increased reticulocyte count = HAs unless they have parvovirus or other reason they cant make RBCs​
Increased unconjugated bilirubin ​
Increased LDH (lactate dehydrogenase) = from haemolysed RBCs​
Low serum haptoglobin​ = protein that binds free haemoglobin ​
Increased urobilinogen​
Increased urinary hemosiderin = iron from Hb that gets picked up by epithelial cells in urinary tract​
Abnormal blood film

Question 12

Blood film for haemolytic anaemia

Answer 12

Reticulocytes - (Supravital stain)
Polychromasia​
Nucleated RBC​

Question 13

Classifying Haemolytic Anaemias​

Answer 13

If looking at inheritance​:
Inherited​ = Hereditary spherocytosis​
Acquired​ = Paroxysmal nocturnal haemoglobinuria​

If looking at site of RBC destruction:
Intravascular​ = Thrombotic thrombocytopenic purpura​
Extravascular​ = Autoimmune haemolysis​

If looking at origin of RBC damage:
Intrinsic​ = G6PD deficiency​
Extrinsic = Delayed haemolytic transfusion reaction​

Question 14

Describe RBC destruction

Answer 14

If extravascular (in macrophages) = into globin (broken into AAs) + iron (circulation, binds transferrin) + protoporphyrin

→ bilirubin (CO released as expired air)

→ bilirubin → (in peripheral blood) bilirubin - UC

→ bilirubin glucuronides through liver
→ stercobilinogen (faeces) → urobilinogen (urine)

Intravascular = RBC into haemoglobinaemia then methaemalbuminaemia then haemoglobinuria then haemosiderinuria

Question 15

Vertical interaction function and defects in it

Answer 15

Stabilize lipid membrane:

Spectrin-ankyrin-band 3 interactions, Spectrin-protein 4.1R–junctional complex linkages
Skeletal proteins/-ve proteins of inner LBL

Spectrin, band 3, protein 4.2 + ankyrin = hereditary spherocytosis

Question 16

Horizontal interaction function and defects in it

Answer 16

Support structural integrity of the red cell, including after exposure to shearing:
(involving the spectrin heterodimer associations)

Protein 4.1​ + glycophorin C​ + spectrin – HPP = hereditary elliptocytosis

Question 17

What is hereditary spherocytosis and its effects

Answer 17

Common hereditary haemolytic anemia​
Inherited in autosomal dominant fashion (75%) ​
Defects in proteins involved in vertical interactions between the membrane skeleton and the lipid bilayer​
Decreased membrane deformability ​
Bone marrow makes biconcave RBC, but as membrane is lost, the RBC become spherical

Question 18

Hereditary spherocytosis vs AI haemolysis distinction

Answer 18

No central pallor = same look as AI haemolysis

DAT (test) = look for AB on red cell +ve in AIH and –ve in spherocytosis

Question 19

Clinical features of hereditary spherocytosis

Answer 19

Asymptomatic to severe haemolysis​
Neonatal jaundice​
Jaundice, splenomegaly, pigment gallstones​
Reduced eosin-5-maleimide (EMA) binding – binds to band 3​
Positive family history​
Negative direct antibody test

Question 20

Management of hereditary spherocytosis

Answer 20

Monitor​, Folic acid​, Transfusion​, Splenectomy – not in small children = important for immunity

Question 21

RBC metabolic pathways​

Answer 21

Glycolysis –energy- ATP ​
Na/K pump​
3 Na+ out 2 K+ in ​
ATP to ADP+Pi​

HMS – reducing power -NADPH/GSH​

Rapoport Luebering shunt –​

2,3 Bi-PhosphoGlycerate (2,3 BPG) – modulates O2 binding to Haemoglobin

Question 22

Role of the HMP shunt

Answer 22

Generates reduced glutathione​

Protects the cell from oxidative stress

Question 23

Effects of oxidative stress

Answer 23

Oxidation of Hb by oxidant radicals​

Resulting denatured Hb aggregates & forms Heinz bodies – bind to membrane​

Oxidised membrane proteins – reduced RBC deformability​

Question 24

What is G6PD, its spread, clinical features

Answer 24

Hereditary, X-linked disorder ​
Common in African, Asian, Mediterranean and Middle Eastern populations ​
Mild in African (type A), more severe in Mediterraneans (type B)​
Clinical features range from asymptomatic to acute episodes to chronic haemolysis

Question 25

G6PD oxidative precipitants

Answer 25

``` Infections​ Fava/ broad beans​ Many drugs e.g.:​ Dapsone​ Nitrofurantoin​ Ciprofloxacin​ Primaquine ```

Question 26

G6PD features

Answer 26

``` Haemolysis​ Film:​ - Bite cells​ - Blister cells & ghost cells​ - Heinz bodies (methylene blue)​ Reduced G6PD activity on enzyme assay​: - May be falsely normal if reticulocytosis ```

Question 27

Oxidative haemolysis definition

Answer 27

Destruction of circulating human erythrocytes exposed to oxidant stress

Question 28

Pyruvate Kinase Deficiency​ - cause and effects

Answer 28

``` PK required to generate ATP​ Essential for membrane cation pumps (deformability)​ Autosomal recessive​ Chronic anaemia​ - Mild to transfusion dependent​ - Improves with splenectomy​ ```

Question 29

Hb structure

Answer 29

Hb structure = Haem (Fe2+ + protoporphyrin IX) + globin (2ɑ + 2β) HbA = ɑ2β2, HbA2 = ɑ2δ2 + HbF = ɑ2γ2

Question 30

Quantitative - thalassaemias = define

Answer 30

Production increased/ decreased amount of a globin chain (structurally normal)​

Question 31

Qualitative – variant haemoglobins = define

Answer 31

Production of a structurally abnormal globin chain​ HbS - ↓solubility, polymerisation Hb Koln - ↓stability, Heinz body formation HbC - ↓solubility, crystallisation

Question 32

Thalassaemias - define

Answer 32

Imbalanced alpha and beta chain production​

Question 33

Effect of excess unpaired globin chains

Answer 33

Excess unpaired globin chains are unstable​ - Precipitate and damage RBC and their precursors​ - Ineffective erythropoiesis in bone marrow​ - Haemolytic anaemia

Question 34

Beta thalassaemias​ - chance

Answer 34

Autosomal recessive = ¼ chance​

Question 35

Diagnosis of thalassaemia trait​

Answer 35

``` Asymptomatic​ Microcytic hypochromic anaemia​ Low Hb, MCV, MCH ​ Increased RBC​ Often confused with Fe deficiency​ HbA2 increased in b-thal trait –(diagnostic)​ a-thal trait often by exclusion​ globin chain synthesis (rarely done now)​ DNA studies (expensive) ```

Question 36

Beta Thalassaemia Major​ effect if not transfused

Answer 36

Transfusion dependent in 1st year of life If not transfused = Failure to thrive,​ Progressive hepatosplenomegaly,​ Bone marrow expansion – skeletal abnormalities,​ Death in 1st 5 years of life from anaemia

Question 37

Side effects of transfusion

Answer 37

Side effects of transfusion = Iron overload​, Endocrinopathies​, Heart failure,​ Liver cirrhosis

Question 38

Sickle cell disease cause

Answer 38

Sickle cell = Point mutation in the β globin gene: glutamic acid → valine = Insoluble haemoglobin tetramer when deoxygenated → polymerisation​ = “Sickle” shaped cells​

Question 39

Clinically significant sickling syndromes

Answer 39

Clinically significant sickling syndromes:​ HbSS​ HbSC​ HbS-D Punjab​ HbS- O Arab​ HbS- β thalassaemia

Question 40

SCD acute complications

Answer 40

``` Stroke: ischaemic & haemorrhagic Cholecystitis​ Hepatic sequestration​ Dactylitis​ Bone pain & infarcts​ Osteomyelitis​ Leg ulcers​ Aplastic crisis​ Priapism​ Haematuria: papillary necrosis​ Splenic sequestration​ Chest syndrome​ Retinal detachment​ Vitreous haemorrhage ```

Question 41

SCD chronic complications

Answer 41

``` Silent infarcts​ Pulmonary hypertension​ Chronic lung disease, bronchiectasis​ Erectile dysfunction​ Azoospermia​ Chronic pain syndromes Delayed puberty​ Leg ulcers​ Avascular necrosis​ Chronic renal failure​ Retinopathy, visual loss​ Moya-moya​ ```

Question 42

Clinical features of SCD

Answer 42

``` Painful crises​ Aplastic crises​ Infections Acute sickling:​ - Chest syndrome​ - Splenic sequestration​ - Stroke​ Chronic sickling effects:​ - Renal failure​ - Avascular necrosis bone ```

Question 43

Laboratory features of SCD

Answer 43

``` Anaemia​ - Hb often 65-85​ Reticulocytosis​ Increased NRBC​ Raised bilirubin​ Low creatinine ```

Question 44

SCD diagnosis

Answer 44

Diagnosis = Solubility test​, Expose blood to reducing agent​, Hb S precipitated,​ Positive in trait and disease Or electrophoresis to look at structure

Question 45

Autoimmune haemolysis - features

Answer 45

Idiopathic​ - cause unknown - Usually warm​ - Rare cause of hemolysis precipitated by antibodies directed against blood group antigens, most commonly IgG + react with proteins on the surface of RBC at normal body temp (warm agglutinins) (IgM​ as well) Drug-mediated​ Cancer associated​ - LPDs (Lymphoproliferative disorders)q

Question 46

Alloimmune haemolysis - features

Answer 46

Transplacental transfer:​ Haemolytic disease of the newborn:​ - D, c, L​ ABO incompatability​ ``` Transfusion related:​ Acute haemolytic transfusion reaction​ - ABO​ Delayed haemolytic transfusion reaction​ - E.g Rh groups, Duffy​ ```

Question 47

Non-immune acquired haemolysis​ - causes

Answer 47

Paroxysmal nocturnal haemoglobinuria​ Fragmentation haemolysis:​ - Mechanical​ - Microangiopathic haemolysis​ 1. Disseminated intravascular coagulation​ 2. Thrombotic thrombocytopenic purpura​ Other:​ Severe burns​ Some infections: e.g. malaria​