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MEH * > S5 Haemopoiesis Gone Wrong > Flashcards

S5 Haemopoiesis Gone Wrong Flashcards

1
Q

What can overproduction of cells be caused by?

A
  • myeloproliferative disorders

* physiological reactions

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2
Q

What are 4 examples of myeloproliferative disorders?

A
  • essential thrombocythaemia
  • polycythaemia vera
  • myelofibrosis
  • chronic myeloid leukaemia
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3
Q

What mutation can cause myeloproliferative disorders?

A

Specific point mutation in one copy of the Janus kinase 2 gene (JAK2) - codes for a cytoplasmic tyrosine kinase which causes increased proliferation and survival of haemopoietic precursors

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4
Q

What is Polycythaemia Vera?

A

High haematocrit or raised cell mass
(Some also have high platelet and neutrophil count)
JAK2 mutation is present in 95% of patients
Equal in men (haematocrit >0.52) and women (haematocrit >0.48), median age 60yrs

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5
Q

What are the clinical features of Polycythaemia Vera?

A
  • significant cause of arterial thrombosis
  • venous thrombosis
  • haemorrhage into skin/GI tract
  • pruritis (blood in peripheries is thicker)
  • splenic discomfort, splenomegaly
  • gout
  • can go onto myelofibrosis or acute leukaemia
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6
Q

How do you manage Polycythaemia Vera?

A
  • venesection to maintain the haematocrit below 0.45
  • aspirin (75mg)
  • manage the CVS risk factor
  • sometimes consider drugs to reduce overproduction of cells
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7
Q

What is polycythaemia?

A

An increase in circulating red cell concentration typified by a persistently raised haematocrit

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8
Q

What can cause red cell concentration to increase?

A
  • relative - normal red cell mass, but a reduced plasma volume
  • absolute - increase in red cell mass - primary or secondary?
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9
Q

What are primary and secondary increases in red cell mass (absolute) - Polycythaemia?

A

Primary - Polycythaemia Vera

Secondary - driven by erythropoietin (EPO) production (in response to hypoxia or due to an abnormally high affinity for Hb)

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10
Q

What is essential thrombocythaemia?

A

High platelet count (excess platelets in blood)
(Also large and excess megakaryocytes in bone marrow)

Can lead to thrombosis

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11
Q

How do you manage essential thrombocythaemia?

A
  • manage CVS risk
  • aspirin
  • give hydroxycarbomide to high risk patients to return platelet count to normal
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12
Q

What classes as a high risk patient with essential thrombocythaemia?

A
  • over 60 yrs
  • have a platelet count of over 1500
  • have disease related thrombosis/haemorrhage
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13
Q

If there is a high platelet count, what should you do before assume into essential thrombocythaemia?

A

Look for and excuse any reaction causes e.g.

  • infection
  • inflammation
  • haemorrhage
  • cancer
  • redistribution of platelets after a splenectomy or in hyposplenism

Is it persistent rather than transient?

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14
Q

What does myelofibrosis cause?

A

Causes massive splenomegaly with/without hepatomegaly due to extramedullary haemopoiesis

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15
Q

What is myelofibrosis?

A

Fibrosis in bone marrow tissue so there is little space for haemopoiesis

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16
Q

What do RBCs look like on a blood film for myelofibrosis?

A

Tear drop shaped as they’re squeezed out of the bone marrow

17
Q

How can myelofibrosis occur?

A
  • as an end result of Polycythaemia Vera or essential thrombocythaemia
  • as a primary disease
18
Q

What are the clinical features of myelofibrosis?

A
  • if patient has advanced disease have severe symptoms - fatigue an sweats
  • due to splenomegaly experience pain, early satiety (fill up quickly as speed is reducing stomach size) and splenic infarction
  • can transform into leukaemia
  • early death
19
Q

How do you manage chronic marrow failure?

A

Blood transfusions

20
Q

What does a patient with chronic myeloid leukaemia present with? Who is it more common in?

A

Presents with high WCC, symptomatic splenomegaly, hyperviscosity and bone pain

Disease in adults (rare in children)

21
Q

What can you see on the blood film (and marrow) for someone with chronic myeloid leukaemia?

A

Excess of all myeloid series from blast through to fully mature neutrophils

22
Q

What drug can be used to treat chronic myeloid leukaemia? What used to be used as treatment?

A

Imatinib - inhibits BCR-abl fusion from phosphorylating the substrate which switches on a receptor tyrosine kinase that drives proliferation

Previously standard treatment was bone marrow transplant (not very good treatment)

23
Q

What is pancytopenia?

A

Reduction in white blood cells, red blood cells and platelets

24
Q

How can pancytopenia arise?

A
  • reduced production

* increased removal

25
Q

How can pancytopenia arise from reduced production?

A
  • B12/folate deficiency
  • bone marrow infiltration by malignancy
  • marrow fibrosis
  • radiation
  • drugs
  • viruses
  • idiopathic aplastic anaemia
  • congenital bone marrow failure
26
Q

How can pancytopenia arise from increased removal?

A
  • immune destruction (rare)
  • splenic pooling (leads to hypersplenism and splenomegaly)
  • haemophagocytosis (very rare)
27
Q

What is aplastic anaemia?

A

Pancytopenia with a hypocellular bone marrow - not caused by an abnormal infiltrate or an increase in reticulin (fibrosis)

Autoimmune disease - bone marrow fails to produce RBC, WBC and platelets

28
Q

Is aplastic anaemia hard or easy to cure?

A

Hard (immune treatments and bone marrow transplant) but still a high mortality rate (deaths due to neutropenic infection or bleeding)

29
Q

What are the 3 stages in platelet action?

A
  1. Adhesion - to damage endothelial wall (and do vWF - activated clotting)
  2. Activation - change in shape from disc, release of granules
  3. Aggregation - clumping together of more platelets to form a ‘plug’
30
Q

What are the two types of platelet disorders?

A
  • quantitative - low number of platelets

* qualitative - normal number but defective function (thrombocythaemia)

31
Q

How can you get thrombocytopenia?

A
  • acquired (common) - decreased platelet production, increased platelet consumption, increased platelet destruction
  • inherited (rare syndromes)
32
Q

How can platelet production be decreased?

A
  • B12 or folate deficiency
  • acute leukaemia or aplastic anaemia
  • liver failure (reduced production of thrombopoietin)
  • sepsis
  • cytotoxic chemotherapy
33
Q

How can platelet consumption be increased?

A
  • massive haemorrhage
  • disseminated intravascualar coagulation (DIT) in sepsis
  • thrombotic thrombocytopenic purpura (clotting in small blood vessels)
34
Q

How can platelet destruction be increased?

A
  • autoimmune thrombocytopenic purpura (blood doesn’t clot normally)
  • drug induced e.g. heparin
  • hypersplenism - increased destruction and splenic pooling of platelets
35
Q

What are the consequences of severe thrombocytopenia?

A
  • generally asymptomatic until platelet count is below 30
  • easy bruising
  • petechiae and purpura
  • mucosal bleeding
  • severe bleeding after trauma
  • intracranial haemorrhage
36
Q

Why doesn’t a platelet transfusion work with immune thrombocytopenic purpura?

A

Transfused platelets are destroyed by spleen as well

37
Q

What can cause disorders of platelet function?

A
  • hereditary (rare)
  • acquired (common) - aspirin, NSAIDS, clopidogrel (decrease) uraemia (blood in urine)(decrease), myeloma, myeloproliferative disorders (increase)

MEH * (22 decks)

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