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Block 5 > 1.4 Red cell disorders 1 > Flashcards

1.4 Red cell disorders 1 Flashcards

1
Q

define anaemia

A

Reduction of Hb due to quantitative or qualitative impairment in red cell production

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2
Q

What is the normal Hb in adult male and females?

A

Male: 135-180
Female: 115-160

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3
Q

What are the clinical features of haemolytic anaemia?

A

Pallor
Jaundice
Splenomegaly
Gallstones (pigment from Hb)

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4
Q

What are spherocytes?

A

red cells that are ball shaped instead of biconcave

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5
Q

What are poikilocytes?

A

misshapen RBCs

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6
Q

What is polychromasia?

A

fragmented RBCs

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7
Q

What is reticulocytosis?

A

Increase in reticulocytes (immature RBCs)

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8
Q

What is thalassaemia?

A

Imbalance in the globin chains of Hb

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9
Q

What is haemoglobinopathy?

A

Structural abnormalities in globin molecule due to point mutations

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10
Q

What is the normal Hb structure?

A

Tetramer of two alpha and two beta chains, each of which has a heme molecule to which an Fe is attached

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11
Q

What is haemoglobin F?

A

Hb in foetus which has 2 alpha and 2 gamma chains (rather than beta like in adults HbA)

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12
Q

What is haemaglobin A2?

A

2 alpha and 2 delta chains

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13
Q

Which chromosomes encode the Hb genes and which ones encode which?

A

Chromosome 11: beta cluster, delta and 2 fetal gamma genes

Chromosom 16: alpha cluster

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14
Q

How does Hb change from foetus to adult?

A

Hb F consists of alpha chains and gamma chains which predominate until the time of birth. After birth the gamma chains will be replaced by beta chains

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15
Q

What tests can you use for Hb samples?

A

Alkaline gel electrophoresis
Acid gel electrophoresis
High performance liquid chromatography

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16
Q

What are the clinical features of beta thalassaemia major?

A 
Severe anaemia 
Ineffective erythropoiesis 
Extramedullary haemopoiesis 
Hair on end appearance on x-ray (skull)
Enlarged liver and spleen 
Expansion of flat bones of face and skull 
Spontaneous fractures 
Iron overload 
Reduced growth 
Endocrinopathy 
Delayed puberty
17
Q

What are the lab features of beta thalassaemia major?

A

hypo-chromic microcytic Anaemia
target cells, NRBCs
Marrow: red cell hyperplasia, increased iron
Most of Hb is HbF (A1 replaced by F)

18
Q

What is the treatment for beta thalassaemia major?

A

Long term transfusions
Iron chelation therapy (desferrioxamine SC or Deferasirox oral)
Allogenic marrow transplant
MRI imaging of liver and heart for iron content

19
Q

What is Beta thalassaemia intermedia?

A

Clinical syndrome which has traits of major but wil less severe clinical outcomes. Due to different genotypes such as HbE/B

20
Q

What causes beta thalassaemia minor?

A

Single gene defect

21
Q

What are the traits of beta thalassamia minor?

A

hypochromic, microcytic blood film with high RBC count

Raised HbA2 on electrophoresis

Usually picked up on routine tests - asymptomatic just have to think about it for genetic counselling

22
Q

What are the results of alpha thalassaemia?

A

4 genes: hydrops foetalis
3 genes: HbH disease, thalassaemia intermedia
1-2 genes: hypochromic, microcytic blood film and HbH bodies on incubation with dye

23
Q

What causes sickle cell anaemia?

A

Substitution of Valine for glutamic acid in the 6th position of the beta chain (single base change)

24
Q

How do you diagnose sickle cell anaemia?

A

Hb electrophoresis and DNA analysis

25
Q

What are the clinical features of sickle cell anaemia?

A

Pain due to vaso-occlusion (from adhesion)

Infection: pneumonia, osteomyelitis, septic arthritis, parvovirus B19

Respiratory: acute chest syndrome, pulmonary hypertension

CNS: stroke, haematuria

Renal: haematuria, proliferative glomerulopathy, nephrotic syndrome, renal failure

leg ulcers
priapism

26
Q

What is hereditary spherocytosis?

A

a genetic defect in the proteins involved in the interaction between the membrane skeleton and phopholipid bilayer of the RBC memrane

27
Q

What is hereditary spherocytosis?

A

a genetic defect in the proteins involved in the interaction between the membrane skeleton and phopholipid bilayer of the RBC membrane

abnormalities in the ankyrin and spectrin proteins

28
Q

What is the molecular defect in hereditary spherocytosis?

A

usually due to dominant mutations in ANK1 (ankyrin) or spectrin (SPTP)

29
Q

What are the clinical features of hereditary spherocytosis?

A 
pallor 
jaundice 
splenomegaly 
gallstones 
leg ulcers 
aplastic crisis
(will depend on age)
30
Q

What is used to diagnose hereditary spherocytosis?

A

Anaemia with spherocytosis
Increased osmotic fragility
positive cryohaemolysis test
flow cytometery

31
Q

What is the treatment for hereditary spherocytosis?

A

often not required but can be splenectomy

cholecystectomy for gallstones

32
Q

What is the pathophysiology of G-6PD deficiency?

A

Defective production of NADPH
Lower levels of reduced glutathione (GSH)
Oxidant stress
Methaemoglobin forms (cant carry oxygen)
Hb denatured
RBC haemolysis

33
Q

What is the clinical presentation of G-6PD deficiency?

A 
Chronic haemolytic anaemia 
Splenomegaly 
Neonatal jaundice 
Favism (precipitate haemolytic crisis)  
Primaquin sensitivity (malaria drug) 
Acute intravascular haemolysis due to drugs
34
Q

What will you see on a blood film with G-6PD deficiency?

A

Bite or blister cells - denatured Hb removed laving a pitted out pocket

35
Q

What drugs should G-6PD deficient people avoid?

A

Anti-malarial, anti-diabetic and antibiotics

36
Q

What happens in pyruvate kinase deficiency?

A

reduction in ATP in RBCs leading to the cells becoming rigid. This causes splenic trapping and a right shift in the Hb dissociation curve due to the build up of 2,3 BPG

37
Q

What are the clinical features or pyruvate kinase deficiency?

A

Haemolytic anaemia and jaundice in the newborn
Splenomegaly
Pigment gallstones

38
Q

What is the treatment of pyruvate kinase deficiency?

A

not needed in mild cases
blood transfusion
Splenectomy
Potential for gene therapy

Block 5 (35 decks)

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