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4th year passmedicine by topic > Haemolytic Anaemia > Flashcards

Haemolytic Anaemia Flashcards

Thalassaemias covered in Microcytic Anaemia deck

1
Q

How is sickle cell anaemia inherited?

A

autosomal recessive condition

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2
Q

What is sickle cell anaemia?

A

synthesis of an abnormal haemoglobin chain termed HbS

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3
Q

Which form of sickle cell offers some protection against malaria?

A

heterozygous

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4
Q

Around what% of UK Afro-Caribbean’s are carriers of HbS

A

10%

HbS - Heterozygous

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5
Q

When are heteroxygote carriers severly symptomatic (cikle cell)

A

When hypoxic

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6
Q

In sickle cell symptoms in homozygotes don’t tend to develop until

A

4-6 months

when the abnormal HbSS molecules take over from fetal haemoglobin.

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7
Q

Pathophysiology of sickle cell anaemia?

A

abnormal gene for beta-globin on chromosome 11
Polar amino acid glutamate is substituted by non-polar valine in each of the two beta chains. This decreases the water solubility of deoxy-Hb
In the deoxygenated state the HbS molecules polymerise and cause RBCs to sickle

HbAS patients sickle at p02: 2.5 - 4 kPa

HbSS patients at p02: 5 - 6 kPa

sickle cells are fragile and haemolyse; they block small blood vessels and cause infarction

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8
Q

definitive diagnosis of sickle cell disease is

A

haemoglobin electrophoresis

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9
Q

Name sickle cell crises?

A 
thrombotic, 'painful crises'
sequestration
acute chest syndrome
aplastic
haemolytic
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10
Q

Sickle cell anaemia is characterised by

A

periods of good health with intervening crises

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11
Q

What are thrombotic crises precipitated by?

A

infection, dehydration, deoxygenation

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12
Q

How are thrombotic crises diagnosed?

A

painful vaso-occlusive crises should be diagnosed clinically - there isn’t one test that can confirm them although tests may be done to exclude other complications

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13
Q

What complications can you get in thromotic crises?

A

infarcts occur in various organs including the bones (e.g. avascular necrosis of hip, hand-foot syndrome in children, lungs, spleen and brain

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14
Q

What is a sequestration crises?

A

sickling within organs such as the spleen or lungs causes pooling of blood with worsening of the anaemia

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15
Q

Symptoms of acute chest syndrome?

A

dyspnoea, chest pain, pulmonary infiltrates, low pO2

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16
Q

the most common cause of death after childhood is due to?

A

acute chest syndrome

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17
Q

Aplastic crises is caused by what? What would you see investigations wise?

A

caused by infection with parvovirus

sudden fall in haemoglobin

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18
Q

How common is Haemolytic crises? What would you see investigations wise?

A

rare

fall in haemoglobin due an increased rate of haemolysis

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19
Q

What is the general management of sickle cell crises?

A

analgesia e.g. opiates
rehydrate
oxygen
consider antibiotics if evidence of infection
blood transfusion
exchange transfusion: e.g. if neurological complications

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20
Q

What is the main stay of long term management of sickle cell anaemia?

A

hydroxyurea

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21
Q

How does hydroxyurea work?

A

increases the HbF levels and is used in the prophylactic management of sickle cell anaemia to prevent painful episodes

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22
Q

NICE CKS suggest that sickle cell patients should receive which vaccine?

A

the pneumococcal polysaccharide vaccine every 5 years

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23
Q

the majority of adults patients with sickle-cell will have an atrophied spleen due to repeated infarction

A

true

although you can get splenomegaly too

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24
Q

What are the general classifications of haemolytic anaemias?

A

Hereditary causes
Acquired: immune causes
Acquired: non-immune causes

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25
Q

Hereditary haemolytic anaemias can be subdivided into

A

membrane, metabolism or haemoglobin defects

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26
Q

Hereditary causes of haemolytic anaemias?

A

membrane: hereditary spherocytosis/elliptocytosis
metabolism: G6PD deficiency
haemoglobinopathies: sickle cell, thalassaemia

27
Q

Acquired: immune causes of haemolytic anaemias?

A

autoimmune: warm/cold antibody type
alloimmune: transfusion reaction, haemolytic disease newborn
drug: methyldopa, penicillin

28
Q

Acquired: NON immune causes of haemolytic anaemias?

A 
microangiopathic haemolytic anaemia (MAHA): TTP/HUS, DIC, malignancy, pre-eclampsia
prosthetic cardiac valves
paroxysmal nocturnal haemoglobinuria
infections: malaria
drug: dapsone
29
Q

What is the most common hereditary haemolytic anaemia in people of northern European descent?

A

Hereditary spherocytosis

30
Q

What is the inheritance pattern if heriditary spherocytosis?

A

autosomal dominant

31
Q

What is hereditary spherocytosis?

A

defect of red blood cell cytoskeleton
the normal biconcave disc shape is replaced by a sphere-shaped red blood cell

red blood cell survival reduced as destroyed by the spleen

32
Q

How does hereditary spherocytosis present?

A 
failure to thrive
jaundice
gallstones
splenomegaly
aplastic crisis 
degree of haemolysis variable
MCHC elevated
33
Q

How do you diagnose hereditary spherocytosis?

A

patients with a family history of HS, typical clinical features and laboratory investigations (spherocytes, raised mean corpuscular haemoglobin concentration [MCHC], increase in reticulocytes) do not require any additional tests

EMA binding test is diagnostic

for atypical presentations electrophoresis analysis of erythrocyte membranes is the method of choice

34
Q

How do you manage hereidtary spherocytosis?

A

acute haemolytic crisis: treatment is generally supportive, transfusion if necessary
longer term treatment: folate replacement, splenectomy

35
Q

What would you see in hereditary spherocytosis on blood film?

A

Spherocytes (round, lack of central pallor)

36
Q

Lab investigations for hereditary spherocytosis?

A

spherocytes, raised mean corpuscular haemoglobin concentration [MCHC], increase in reticulocytes

37
Q

What is the typical history of heritary spherocytosis?

A
  • Neonatal jaundice
  • Chronic symptoms although haemolytic crises may be precipitated by infection
  • Gallstones
  • Splenomegaly is common
38
Q

G6PD deficiency inheritance?

A

Male (X-linked recessive)

39
Q

G6PD deficiency ethnicity commonest in?

A

African + Mediterranean descent

40
Q

G6PD deficiency typical history?

A

• Neonatal jaundice
• Infection/drugs precipitate haemolysis
• Gallstones
splenomegaly may be present

41
Q

G6PD deficiency on blood film?

A

Heinz bodies

Bite and blister cells may also be seen

42
Q

What is the diagnostic test for G6PD deficiency?

A

Measure enzyme activity of G6PD

43
Q

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the commonest red blood cell enzyme defect.

A

true

44
Q

What can precipitate a crisis in G6PD deficiency?

A

Many drugs can precipitate a crisis as well as infections and broad (fava) beans

45
Q

What protects RBCs from oxidative damage?

A

glutathine

(protects red blood cells from oxidative damage by oxidants such as superoxide anion (O2-) and hydrogen peroxide

46
Q

What is important for converting oxidizied glutathine back to it’s reduced form?

A

NADPH

47
Q

What does Glucose-6-phosphate dehydrogenase do?

A

G6PD is the first step in the pentose phosphate pathway, which converts glucose-6-phosphate→ 6-phosphogluconolactone
this reaction also results in nicotinamide adenine dinucleotide phosphate (NADP) → NADPH
i.e. glucose-6-phosphate + NADP → 6-phosphogluconolactone + NADPH

48
Q

What is the pathophysiology of G6PD deficiency?

A

↓ G6PD → ↓ reduced NADPH → ↓ reduced glutathione → increased red cell susceptibility to oxidative stress

49
Q

After an acute episode in G6PD deifiency, when whould enzyme levels be checked? WHy?

A

levels should be checked around 3 months after an acute episode of hemolysis

RBCs with the most severely reduced G6PD activity will have hemolysed → reduced G6PD activity → not be measured in the assay → false negative results

50
Q

Which drugs causing haemolysis in G6PD defiency?

A

anti-malarials: primaquine
ciprofloxacin
sulph- group drugs: sulphonamides, sulphasalazine, sulfonylureas

51
Q

Some drugs thought to be safe in G6PD defiency?

A 
penicillins
cephalosporins
macrolides
tetracyclines
trimethoprim
52
Q

Autoimmune haemolytic anaemia (AIHA) may be divided in to?

A

‘warm’ and ‘cold’ types, according to at what temperature the antibodies best cause haemolysis.

53
Q

What causes Autoimmune haemolytic anaemia?

A

most commonly idiopathic but may be secondary to a lymphoproliferative disorder, infection or drugs

54
Q

AIHA is characterised by which test?

A

positive direct antiglobulin test (Coombs’ test)

55
Q

In warm AIHA the antibody is usually what?

A

IgG

56
Q

In warm AIHA haemolysis occurs at which temp and which body sites?

A

body temperature and haemolysis tends to occur in extravascular sites, for example the spleen

57
Q

Management options for warm AIHA?

A

steroids, immunosuppression and splenectomy

58
Q

Causes of warm AIHA?

A

autoimmune disease: e.g. systemic lupus erythematosus*

neoplasia: e.g. lymphoma, CLL
drugs: e.g. methyldopa

59
Q

The antibody in cold AIHA is usually ? Haemolysis is mediated by?

A

IgM

Haemolysis is mediated by complement

60
Q

In cold AIHA haemolysis occurs at which temp? Which site does this usually occur?

A

4 deg C.

commonly intravascular.

61
Q

Patients respond better to steroids in cold vs warm AIHA

A

false

Patients respond less well to steroids

62
Q

What are the features of cold AIHA?

A

Features may include symptoms of Raynaud’s and acrocynaosis.

63
Q

Causes of cold AIHA?

A

neoplasia: e.g. lymphoma
infections: e.g. mycoplasma, EBV

64
Q

systemic lupus erythematosus can rarely be associated with a mixed-type autoimmune haemolytic anaemia

A

true

4th year passmedicine by topic (96 decks)

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