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Y2 CARDIORESP > Anaemia > Flashcards

Anaemia Flashcards

1
Q

Define haemolysis

A

Increased destruction of RBCs

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2
Q

What are haemolytic anaemias?

A

Group of anaemias in which red cell lifespan is reduced

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3
Q

How could a patient with haemolytic anaemia (low Hb) be treated?

A

Folic acid - increased requirement for erythropoiesis
Splenectomy (if severe) to increase red cell life span

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4
Q

What does an increase in unconjugated bilirubin indicate?

A

Problem with haemolysis of RBCs, a post-blood transfusion reaction, cirrhosis of the liver

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5
Q

What name is given to RBCs that are very round without the usual central pallor?

A

Spherocytyes

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6
Q

What is hereditary spherocytosis?

A

A disruption of vertical linkages in the red cell membrane causing red blood cells to become more spherical shaped

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7
Q

What do polychromatic macrocytes look like?

A

Larger and more blue than normal red cells

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8
Q

What are the four primary underlying mechanisms of anaemia?

A

reduced production of red cells/haemoglobin by the bone marrow
(b) reduced survival of red cells in the circulation (haemolysis).
(c) loss of blood from the body
(d) pooling of red cells in a very large spleen.

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9
Q

What are the symptoms associated with hereditary sopherocytosis?

A

Increased red cell osmotic fragility
Jaundice
Gall stones

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10
Q

What is seen on the blood film of someone with hereditary spherocytosis?

A

Spherocytes
Polychromatic macrocytes
High reticulocyte count
High unconjugated bilirubin

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11
Q

What test involving water can be done to test for hereditary spherocytosis?

A

Osmotic fragility test - reveals spherocytosis fragility in hypotonic solution

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12
Q

What does an increased unconjugated bilirubin suggest?

A

Pre-hepatic cause of jaundice
Caused by haemolysis

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13
Q

What does an increased conjugated bilirubin suggest?

A

Decreased elimination of bilirubin by hepatocytes

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14
Q

What are the common complications associated with haemolytic anaemia?

A

Gall stones
- increased breakdown of Hb to BR
- can lead to jaundice

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15
Q

How is hereditary spherocytosis treated?

A

Folic acid
Transfusion if severe
Splenectomy if severe but avoid if possible

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16
Q

What is the lab evidence for haemolysis/ haemolytic anaemia?

A

LDH inc
Unconjugated hyperbilirubinaemia
Reduced Haptoglobins
Increased MCV
Reticulocytosis

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17
Q

Acquired haemolytic anaemia is a result of what?

A

A problem in the RBC environment (plasma/ vasculature)

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18
Q

What environmental factors can damage RBCs?

A

•Environmental factors can damage RBCs
•Non-immune
> microangiopathic
> haemolytic uraemic syndrome
> malaria
> snake venom
> drugs
•Immune mediated
> auto immune
> allo immune (post blood transfusion)

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19
Q

Haemolytic anaemia can be categorised into having what 2 causes?

A

Acquired or inherited

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20
Q

Inherited haemolytic anaemia is the result of what?

A

A defect in RBC themselves

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21
Q

Wheat RBC defects can cause inherited haemolytic anaemia?

A

• abnormal cell membrane - eg. Hereditary spherocytosis
• abnormal Hb - eg. sickle cell
• defect in glycolytic pathway - eg. pyruvate kinase deficiency
• defect in enzymes of pentose shunt - eg. G6PD deficiency

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22
Q

How do we confirm wether the mechanism of haemolytic anaemia is immune or not ?

A

DAT: direct antiglobulin test
- autoantibodies to erythrocytes antigens can be detected
- a rabbit antibody to human immunoglobulin is added to the sample
- positive DAT confirms immune mechani

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23
Q

What is autoimmune haemolytic anaemia?

A

Patient develops auto-antibodies against their own RBCs via a Type II hypersensitivity reaction

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24
Q

What causes autoimmune haemolytic anaemia?

A

• Idiopathic
• Associated with disorders of immune system:
> Systemic auto immune disease (SLE)
> Underlying lymphoid cancers (lymphoma)

25
Q

What is the clinical presentation of autoimmune haemolytic anaemia?

A

Normocytic anaemia with a raised bilirubin
• Elevated Reticulocytes/LDH/unconjugated bilirubin
• MCV borderline raised
• DAT positive
Clinical history and exam may point to acquired or inherited (eg sickle cell)

26
Q

Where is a G6PD deficiency most common?

A

Middle East, Africa, Southeast Asia and Sardinia

27
Q

Give three examples of anaemia caused by reduced red cell production?

A

Iron deficiency anaemia
Anaemia of chronic disease
Megaloblastic anaemia (B12 deficiency)

28
Q

Give three examples of an anaemia cause by reduced cell of red cells?

A

Hereditary spherocytosis
Autoimmune haemolytic anaemia
G6PD deficiency

29
Q

What is a G6PD deficiency?

A

G6PD deficiency
x-linked recessive disease
- increases RBC sensitivity to oxidative stress (G6PD is part of the pentose shunt which usually protects from oxidant damage)
- can lead to acute haemolytic anaemia (usually triggered)

30
Q

What is the clinical presentation of a G6PD deficiency?

A

• signs of haemolytic anaemia
> unconjugated hyperbilirubinaemia
> reticulocytosis
> high MCV
• blood film
> ghost cells – indicate intravascular haemolysis
Heinz bodies

31
Q

What are Heinz bodies and in which anaemia are they most commonly seen?

A

Oxidised, precipitated Hb embedded in membrane of RBCs
Seen in G6PD deficiency
Result of oxidant damage

32
Q

How is G6PD managed?

A

Advice for G6PD deficiency
- Avoid oxidant drugs
- Don’t eat broad beans
- Avoid naphthalene
- Be aware that haemolysis can result from infection

33
Q

What are the three main causes of iron deficiency anaemia?

A

Increased blood loss
Insufficient iron uptake
Increased iron requirements i

34
Q

What can cause insufficient iron intake?

A

Dietary - vegetarians
Malabsorption - coeliac, h.pylori gastritis

35
Q

What are the symptoms associated with iron deficiency anaemia?

A
  • fatigue
  • weakness
  • pale skin
  • shortness of breath
  • headache
  • dizziness
  • koilonychia (spoon nails)
  • glossitis (inflammation of the tongue)
36
Q

What are the differential diagnosis of anaemia with a low MCV?

A

Diff. diagnosis of anaemia with low MCV – iron deficiency anaemia, thalassemia, anaemia of chronic disease

37
Q

What is typically seen in the full blood count for iron deficiency anaemia?

A

Low Hb
Low MCV
Low MCH and MCHC
Low ferritin and serum iron
High transferrin
No HbA2 increase

38
Q

What is typically seen on the blood film for a patient with iron deficiency anaemia?

A

Microcytosis
Hypochromia
Target cells

39
Q

What questions do patients with suspected iron deficiency anaemia need to be asked?

A

• Diet - vegetarian/vegan
• Gastrointestinal symptoms: dysphagia/dyspepsia/abdominal pain, change in bowel habit, haematemesis/rectal bleeding/melaena
• Menstrual history/post-menopausal bleeding
• Weight loss
• Medication - e.g. aspirin/non-steroidal anti-inflammatory drugs (NSAIDs)

40
Q

What investigations are made for someone with weight loss and abdominal pain?

A

• Investigating for blood in the stool
> (Faecal Immunochemical Test, FIT)
• Gastrointestinal (GI) investigations
> Upper GI endoscopy - oesophagus, stomach, duodenum
> Take duodenal biopsy
> Colonoscopy
• Coeliac antibody testing

41
Q

Outline the pathophysiology of anaemia of chronic disease?

A

• hepcidin blocks absorption and release of iron stores
• hepcidin production is increased in inflammatory states
• pro-inflammatory cytokines interfere with production and action of EPO

42
Q

What are the most common causes of anaemia of chronic disease?

A

Infections - TB and HIV
Rheumatoid arthritis and other autoimmune disorders
Malignancy
Inflammation

43
Q

How does anaemia of chronic disease typically present?

A

• blood tests:
- low Hb, low MCV
- low ferritin (low iron)
- low transferrin
- high ESR (inflammation)
• blood film
- hypochromia
- microcytosis
- rouleaux (aggregation due to high ESR)

44
Q

What is a megaloblast?

A

An abnormally large uncleared red cell precursor with an immature nucleus compared to cytoplasm

45
Q

What is megaloblastic anaemia?

A

Type of macrocytic anaemia characterised by an elevated number of megaloblasts in the bone marrow

46
Q

What is the underlying mechanism of megaloblastic anaemia?

A

Failed DNA synthesis leading to asynchronous maturation of nucleus and cytoplasms in RBCs

47
Q

What are the causes of megaloblastic anaemia?

A

CAUSES
• Vitamin B12/Folate deficiency
> required for DNA synthesis
> absence leads to severe anaemia which can be fatal
• Secondary to agents or mutations that impair DNA synthesis
> Drugs: azathioprine cytotoxic chemotherapy
> Folate antagonists: methotrexate
> BM cancers: myelodysplastic syndrome

48
Q

Why does a vitamin B12 deficiency result in anaemia?

A

Vitamin B12 is required for
1. DNA synthesis
2. Integrity of the nervous system
Folic acid is required for
1. DNA Synthesis
2. Homocysteine metabolism

49
Q

Outline the clinical presentation seen in megaloblastic anaemia

A

Clinical presentation of megaloblastic anaemia
• blood test
> low Hb, high MCV
> reticulocytosis
> high LDH
> low vitamin B12 and folate
• blood film
> poikilocytosis
> hyper segmented neutrophils
• neurological issues
• vitiligo

50
Q

What are the 3 mechanisms that cause a vit.B12 deficiency?

A

Reduced intake
Gastric issues
Bowel issues

51
Q

What gastric issues can lead to a vitamin B12 deficiency?

A

Gastrectomy
Autoimmune - pernicious anaemia (anti-IF antibodies)
H.pylori

52
Q

Hat bowel issues can result in a vit.B12 deficiency?

A

Crowns disease
Ileal resection
Tapeworm
Coeliac

53
Q

What examples of reduced availability can cause a folate deficiency?

A

• Dietary
> poverty
> alcoholism
• Malabsorption
> Coeliac disease
> Jejunal resection

54
Q

What examples of increased demand can result in a folate deficiency?

A

Pregnancy
Lactation
Increase in cell turnover - haemolysis

55
Q

How are vit.B12 and folate deficiencies treated?

A

B12 - oral supplements, hydroxocobalmin injections
Folate - oral supplements

56
Q

What neurological disorders are associated with megaloblastic anaemia?

A

• Vitamin B12:
> dementia
> SACD (sub-acute combined degeneration) of spinal cord
• Folic acid:
> developmental neural tube defects

57
Q

What are the common causes of microcytic anaemia?

A
  • Defect in haem synthesis
    • Iron deficiency anaemia
    • Anaemia of chronic disease
  • Defect in globin synthesis (thalassaemia)
    • Defect in α chain synthesis (α thalassaemia)
    • Defect in β chain synthesis (β thalassaemia)
58
Q

What are the common causes of macrocytic anaemia?

A

Common causes of macrocytic anaemia
• Lack of vitamin B12 or folic acid: megaloblastic anaemia
• Use of drugs interfering with DNA synthesis
• Liver disease and ethanol toxicity
• Haemolytic anaemia (reticulocytes increased)

59
Q

What are the most common causes of normocytic anaemia?

A

Common causes of normocytic anaemia
•Recent blood loss
> Gastrointestinal haemorrhage
> Trauma
•Failure of production of red cells
> Early stages of iron deficiency
> Bone marrow failure or suppression (e.g. chemotherapy)
> Bone marrow infiltration (e.g. leukaemia
•Pooling of red cells in the spleen
> Hypersplenism, e.g. liver cirrhosis
> Splenic sequestration in sickle cell anaemia

Y2 CARDIORESP (15 decks)

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