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Haematology AB > Anaemia AB > Flashcards

Anaemia AB Flashcards

1
Q

What is the main source of iron for haematopoiesis?

A

Recycled iron from reticuloendothelial system

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2
Q

Where is most of the body’s iron stored?

A

Hb in circulating red cells

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3
Q

What regulates iron absorption?

A

1) Oxygen tension
2) Intracellular iron levels
3) Systemic iron needs

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4
Q

What is the role of hypoxia-induced factor?

A

Hypoxia-induced factor (HIF-2a)

  • induced by reduced oxygen tension
  • transcriptional control of DMT-1 and ferroportin
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5
Q

What is the role of iron regulatory proteins?

A

Iron regulatory proteins type 1 and 2 (IRPS1/2)

  • responds to intracellular iron level
  • binds to iron-response elements that impact on mRNA stability and translation
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6
Q

What is the role of hepcidin?

A

Hepcidin: binds to ferroportin and induces its degradation

  • Systemic regulation of iron absorption; liver production
  • Regulated by: HFE, TfR2, HJV, inflammation, hypoxia, EPO
  • Acute phase reactant, largely mediated by IL-6
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7
Q

How do hepcidin levels differentiate between iron overload and iron deficiency?

A

Iron overload: hepcidin increased

Iron deficiency: hepcidin reduced

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8
Q

Where is iron absorbed?

A

Duodenum

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9
Q

Iron deficiency anaemia - what do you see on blood film?

A

Microcytic, hypochromic cells, pencil cells, thrombocytosis, increased RDW

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10
Q

Iron deficiency anaemia - what do you see on iron studies?

A 
Transferrin increased
Transferrin saturation decreased
TIBC increased
Ferritin reduced
Soluble transferrin receptor increased (less specific than low ferritin)
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11
Q

Anaemia of chronic disease - what is the mechanism?

A

IL-6&raquo_space; increased hepcidin&raquo_space; ferroportin degraded

Altered or abnormal iron haemostasis
- reduced absorption or trapping in macrophages

Reduced red cell production by bone marrow
- toxicity/cell death of precursors; CK mediated effect

Blunted response to EPO
- reduced production of EPO, reduced receptors, reduced responsiveness

Shortened red cell survival
- erythrophagocytosis; CK and free radical damage

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12
Q

How does soluble transferrin receptor differentiate iron deficiency from anaemia of chronic disease?

A

Increased in iron deficiency anaemia

Normal in anaemia of chronic disease

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13
Q

What factors affect the level of soluble transferrin factor?

A

Soluble transferrin receptor is derived from bone marrow erythroid precursors

Directly proportional to erythropoietic rate

Inversely proportional to iron stores

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14
Q

Blood film - what is the cause of ovalocytes?

A

Megaloblastic anaemia

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15
Q

Megaloblastic anaemia - which drugs cause this?

A

Antifolate drugs
- MTX, pentamidine, TMP

DNA synthesis
- AZA, hydroxyurea, Zidovudine, chemo

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16
Q

Macrocytic anaemia - what are the causes?

A 
B12/folate deficiency
Drugs (antifolate, DNA synthesis)
Reticulocytosis
BM pathology (MDS, myeloma, aplastic anaemia)
Liver disease, EtOH, phenytoin
Copper deficiency
Arsenic
Down syndrome
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17
Q

Macrocytic anaemia - what are some factitious causes?

A

Cold agglutinins
Old sample
Hyper-osmolar state

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18
Q

B12 - where is it absorbed?

A

Terminal ileum

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19
Q

B12 - how is it absorbed?

A

Initially bound by transcobalamin I or haptocorrin (R protein)

Pancreatic enzymes release cobalamin from these and allow binding to intrinsic factor from gastric parietal cells

B12-IF complex binds to receptor (cubulin) in terminal ileum, taken up by receptor-mediated endocytosis and absorped into portal circulation

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20
Q

Pernicious anaemia - what is the mechanism?

A

Autoimmune destruction of gastric mucosa/parietal cells

Leads to reduced acid production and reduced IF

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21
Q

Pernicious anaemia - what are the associations?

A 
Blue eyes, fair hair, northern european
Family history
Blood group A
Vitiligo, thyroid disease, Addison's, hypoparathyroid
Hypogammaglobulinaemia
Gastric carcinoma
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22
Q

Pernicious anaemia - what investigations can you do?

A

Intrinsic factor antibodies - very specific but only 50% sensitive

Parietal cell antibodies - sensitive but not specific (positive in 15% of normal females)

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23
Q

B12 deficiency - causes?

A 
Pernicious anaemia
Nutritional (strict vegans)
Ileal pathology
- Crohn's
- Ileal resection
- Tropical sprue/tapeworm
- Mutation/deficiency of receptor for IF
Gastrectomy
Other
- NO poisoning
- Congenital abnormalities
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24
Q

B12 deficiency - what are the features on blood film?

A 
Macrocytic anaemia 
Hypersegmented neutrophils
- May develop before anaemia develops
Oval macrocytes
Low reticulocyte count
Pancytopaenia may occur
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25
Q

Folate - what is the source?

A

Dietary (only)

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26
Q

Folate - where is it absobed?

A

Small bowel

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27
Q

Folate - how long do the stores last?

A

Months

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28
Q

Folate - where is it stored?

A

> 95% in RBC

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29
Q

Decreased haptoglobin - what are the causes

A 
Haemolysis
Liver failure
Megaloblastic anaemia
Anaemia of chronic disease
Congenital
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30
Q

Microangiopathic haemolytic anaemia - what are the causes?

A 
TTP/HUS
Atypical HUS
Pre-eclampsia
HELLP
Malignant hypertension
Renal allograft rejection
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31
Q

Atypical HUS - what is the cause?

A

Inherited dysregulation of complement system

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32
Q

Atypical HUS - what is the treatment?

A

Eculizumab

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33
Q

TTP - what is the classic pentad?

A 
Haemolysis with red cell fragmentation
Thrombocytopaenia
Fever
Neurological signs
Renal impairment
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34
Q

TTP - what is the pathogenesis?

A
  1. ADAMTS13 deficiency (hereditary or acquired); protease that cleaves vWF
  2. Increased high molecular weight vWF
  3. Abnormal platelet aggregation
  4. Microvascular thrombosis
  5. Tissue ischaemia
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35
Q

TTP - what are the causes?

A 
Idiopathic
Pregnancy
Drugs (CsA, chemotherapy)
Bone marrow transplant
Malignancy
HIV
Familial
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36
Q

TTP - what is the mortality if untreated?

A

> 90% - haematologic emergency

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37
Q

TTP - what is the treatment?

A

PLEX
Avoid platelet transfusions
Immunosuppression

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38
Q

PNH - what is the genetic basis?

A

Rare, acquired clonal disease of haematopoiesis

Somatic mutation in pig-A gene

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39
Q

PNH - what is the mechanism?

A

Defective production of phosphatidylinositol glycan A (PIG-A) which is essential for the formation of the GPI anchor

Loss of several surface proteins that protect the cell from complement-mediated lysis: CD55, CD59

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40
Q

PNH - what is the diagnosis?

A

Flow cytometry (gold standard)

  • CD55 and CD59 on RBC + neutrophils
  • FLAER
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41
Q

PNH - what is the treatment?

A

Transfusions; SCT
Thrombosis management - lifelong after 1st thrombosis
Eculizumab: anti-C5 (targets terminal component of C’ cascade)

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42
Q

Paroxysmal cold haemoglobinuria - causes?

A

Idiopathic
Syphilis
Viral infections

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43
Q

Paroxysmal cold haemoglobinuria - mechanism?

A

Biphasic IgG anti-P antibody (Donath-Landsteiner Antibody) binds RBC at low temperatures

Upon warming, C’ mediated lysis occurs

44
Q

Paroxysmal cold haemoglobinuria - blood film?

A

Red cell agglutination

45
Q

Paroxysmal cold haemoglobinuria - management?

A

Cold avoidance

Splenectomy NOT useful

46
Q

Spherocytes - what conditions are they found in?

A

AIHA

Hereditary spherocytosis

47
Q

Warm AIHA - what are the 6 causes?

A 
Idiopathic
SLE/autoimmune
Lymphoproliferative: CLL/lymphoma
Infection: HCV, CMV
Drugs: methyldopa, antibiotics
Evan's syndrome: combination of autoimmune haemolysis with ITP
48
Q

Warm AIHA - what is the mechanism?

A

Antibodies that react with red cells at 37 degrees- IgG*** +/- complement
- RBC taken up by macrophages in the RE system via Fc receptors

49
Q

Warm AIHA - what are the investigations?

A

Direct antiglobulin test (Coombs test)

- Demonstration of autoantibodies attached to the patient’s red cells

50
Q

DAT - what are the causes of false positive and false negatives?

A

False positives: 10% of hospitalised patients
- Recent transfusion - delayed haemolytic transfusion reaction

False negatives:- IgA or IgM mediated

51
Q

Warm AIHA - what is the treatment?

A

Prednisolone 1mg/kg then taper- First line
IVIG
Folate supplement
Immunosuppression: AZA/6MP
Splenectomy and vaccination - Best second line after steroids
Rituximab

52
Q

Warm AIHA - what are the characteristic findings?

A

Anaemia
Haemolysis
Spherocytes
Splenomegaly

53
Q

Cold AIHA - what is the mechanism?

A

Antibodies that react with RBCs

54
Q

Cold agglutinin disease - what are the causes?

A

Primary
- Associated with MGUS or asymptomatic LPD

Secondary (majority)

  • LPD
  • Mycoplasma
  • EBV
  • Autoimmune
55
Q

Cold agglutinin disease - treatment?

A

Cold avoidance
Chlorambucil if underlying LPD
Rituximab

Does NOT respond to steroids or splenectomy

56
Q

Hereditary spherocytosis - what is the pathology?

A

Loss of VERTICAL interactions
Ankyrin 50%
Spectrin 30%
Band 3 20%

57
Q

Hereditary elliptocytosis - what is the pathology?

A

Loss of HORIZONTAL interactions
Alpha or beta spectrin
Protein 4.1
Band 3

58
Q

South-East Asian Ovalocytosis - what is the pathology?

A

Band 3 abnormality

59
Q

Hereditary spherocytosis - what is the genetic inheritance pattern?

A

Autosomal dominant - Family history in 75%

60
Q

Hereditary spherocytosis - what is the typical presentation?

A

Haemolysis of varying intensity, exacerbated by intercurrent illness
Jaundice
Cholelithiasis
Splenomegaly

61
Q

Hereditary spherocytosis - what is on the blood film?

A

Polychromasia
Prominent spherocytes

Note - typical film and FHx sufficient to establish diagnosis

62
Q

Hereditary spherocytosis - DAT positive or negative?

A

Negative

63
Q

Hereditary spherocytosis - flow cytometry findings?

A

Eosin-5-maleimide (EMA) binding

- Reacts covalently with band 3 protein

64
Q

Hereditary spherocytosis - management?

A

Folate supplementation

Splenectomy

65
Q

Bite cells - what condition are they found in?

A

G6PD deficiency

The ‘bites’ result from removal of denatured Hb by macrophages in the spleen

66
Q

Prickle cells - what condition are they found in?

A

Pyruvate Kinase deficiency

67
Q

G6PD - what is the pathway involved?

A

Hexose-monophosphate pathway: pentose phosphate pathway

68
Q

G6PD deficiency - how does the haemolysis present?

A

Acute haemolytic crisis

Blood film: bite cells, blister cells

69
Q

G6PD deficiency - what is the genetic inheritance and prevalence?

A

X linked

Common

70
Q

G6PD deficiency - what is the mechanism of RBC damage?

A

Susceptibility to oxidative stress

71
Q

Pyruvate kinase deficiency - what is the pathway involved?

A

Glycolytic pathway

72
Q

Pyruvate kinase deficiency - how does the haemolysis present?

A

Chronic haemolysis

73
Q

Pyruvate kinase deficiency - what is the mechanism of RBC damage?

A

Reduced ATP formation&raquo_space; RBC rigidity

74
Q

Pyruvate kinase deficiency - what is the genetic inheritance and prevalence?

A

Autosomal recessive

Rare

75
Q

G6PD deficiency - how to you test for this and what may cause false negative results?

A

Enzyme assays

False negative if reticulocytosis (have higher G6PD levels)

76
Q

G6PD deficiency - what are the precipitants?

A 
Acute illness/infection
Antimalaria drugs - primaquine
Sulphur containing drugs - bactrim, dapsone
Aspirin
Vitamin K analogues
Fava beans
Probenecid
77
Q

Immune thrombocytopaenia - what are the associations?

A 
AIHA
CLL
Autoimmune disease (RA, SLE)
H pylori
Hep C
78
Q

Immune thrombocytopaenia - what is the management?

A

Observation if Plt >30
First line: Prednisolone 1-2mg/kg
IVIG
Splenectomy with vaccination (most effective)

New drugs:
Romiplostim: TPO receptor antagonist
Eltrombopag: TPO mimetic

Other options:
Immunosuppressive: AZA etc
Rituximab
Danazole

79
Q

DIC - what is the prognostic significance in sepsis and severe trauma?

A

Independent predictor of mortality

80
Q

DIC - what are the causes?

A 
Sepsis
Trauma
Malignancy
Pancreatitis
Obstetric (amniotic fluid embolus, abruption, HELLP)
Liver failure
Snake venom
81
Q

DIC - what is the management?

A

Platelet transfusion
FFP (coagulation factors)
Cryoprecipitate (fibrinogen)

82
Q

HIT - what is the mechanism?

A
  1. IgG Ab recognises heparin-PF4 complexes
  2. PF4-Heparin-IgG complex bind to platelet surface
  3. Platelet activation and consumption via Fc receptor
83
Q

HIT - at what time in heparin therapy does it typically develop?

A

5-14 days after commencing heparin

84
Q

HIT - what are the features?

A

Plt fall by >50% but severe thrombocytopaenia uncommon

85
Q

HIT - what is the management?

A

Cease Heparin

Anticoagulate with direct thrombin inhibitor (Bivalirudin, Argatroban)

86
Q

HIT - how do you diagnose?

A

HIT pre-test probability score (4T score)
- Thrombocytopaenia, Timing, Thrombosis, oTher causes

Immunoassay to detect HIT Ab that binds to PF4
- High Sn, low Sp

Functional assay:

  • Serotonin release assay (SRA)
  • Heparin-induced platelet aggregation (HIPA)
87
Q

Target cells - causes?

A

Hb disorders - Thalassaemia
Iron deficiency
Liver disease

88
Q

What chromosome is Hb alpha on?

A

Chromosome 16

89
Q

What chromosome is Hb beta on?

A

Chromosome 11

90
Q

Alpha 0 thal - what is the genetic abnormality?

A

Deletion or inactivation of both alleles on a single chromosome

91
Q

Alpha + thal - what is the genetic abnormality?

A

One allele inactivated on the same chromosome

92
Q

Beta 0 thal - what is the genetic abnormality?

A

Abnormal gene is not expressed

93
Q

Beta + thal - what is the genetic abnormality?

A

Reduced expression of abnormal gene

94
Q

What is in Hb barts?

A

4 gamma chains

95
Q

What is in HbF?

A

2 alpha, 2 gamma chains

96
Q

What is in HbA?

A

2 alpha, 2 beta chains

97
Q

What is in HbH?

A

4 beta chains- In alpha thalassaemia (a - / - - )

98
Q

What is the clinical significance of HbH?

A

High oxygen affinity
Inclusion bodies
Unstable tetrameres
Haemolysis

99
Q

What is in HbA2?

A

2 alpha, 2 delta chains- Increased in beta thalassaemia

100
Q

What are findings on HPLC in beta thalassaemia trait/minor?

A

Increased HbA2
Increrased HbF

Iron deficiency can reduce HbA2 so must assess iron status

101
Q

Beta thalassaemia major - what is the management?

A

Transfusion support: aiming Hb 9-10 to suppress extramedullary haematopoiesisIron chelation therapy
- Desferrioxamine = survival benefit

  • Ferritin >2500 associated with a higher cardiac risk
  • Aim ferritin
102
Q

Desferrioxamine - what are the ADR?

A 
Local reactions (subcut injection)
Deafness
Retinal toxicity
Growth retardation
Infections
103
Q

Sickle Hb - what is the abnormality?

A

CAG to GTG; B-globin gene

Substitutes valine for glutamic acid (HbS)

HbS polymerizes into long fibres on deoxygenation

RBC: distorted, rigid, damaged membranes

104
Q

Sickle cell disease - what is the Hb configutaion?

A

Hb S/S
Hb C/S
Hb beta/S

105
Q

Sickle cell disease - what is the genetics and prevalence?

A

Autosomal recessive

Among most common AR disorders

106
Q

Hyposplenism - what are the features on blood film?

A

Howell-Jolly bodies
Target cells
Occasional acanthocytes
Lymphocytosis

Haematology AB (7 decks)

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