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Flashcards in Haematology Deck (446)
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1

What is polycythaemia (erythrocytosis)?

an increase in Hb, PCV and RBC

2

What is absolute polycythaemia?

true increase in red cell volume, primary or secondary

3

What is relative or stress/spurious polycythaemia?

normal red cell volume, decreased plasma volume, can occur in dehydration and burns

4

Is Hb or PCV a better indicator for polycythaemia?

PCV, as Hb could be low during iron deficiency

5

What is a normal PCV in the blood?

45%

6

Primary causes of polycythaemia?

polycythaemia rubra vera, epo receptor mutations, high oxygen affinity Hb

7

Secondary causes of polycythaemia?

increase in epo from hypoxia, smoking, high altitude, chronic lung disease, anoxia and tumour

8

What is polycythaemia rubra vera?

stem cell disorder with an alteration in the pluripotent progenitor cell, >95% in JAK2 mutations

9

What is the JAK2 gene?

a signal transducer, especially those triggered by haemopoetic growth factors

10

Symptoms of polycythaemia rubra vera?

tiredness, depression, vertigo, tinnitus, hypertension, angina, intermittent claudication, severe itching after hot bath, gout and peptic ulcer, plethora, deep dusky cyanosis, splenohepatomegaly, easy bleeding

11

What complications can polycythaemia lead to?

thrombosis

12

Treatment of polycythaemia?

venesection, chemo (IFN and hydroxyurea), low dose aspirin for thrombosis prophylaxis, anagrelide, radioactive 32P, surgery to prevent leukaemia (splenectomy), keep PCV and platelet count low, cytotoxic myelosuppresion hydroxycarbamide, regular removal of blood, phlebotomy to keep haematocrit

13

How many polycythaemia cases develop into myelofibrosis or AML?

myelofibrosis in 30%
AML in 5%

14

What will investigations show in polycythaemia?

raised haematocrit, Hb, RCC, MCV, raised WCC and platelets, neutrophil leucocytosis, o2 sat >92%, thrombocytosis, splenomegaly,

15

What will bone marrow show in polycythaemia?

bone marrow hypercellular with prominent megakaryocutes, low epo

16

What is the WHO diagnostic criteria for polycythaemia?

2 major and 1 minor or main major and 2 minor

17

What are the major criteria for polycythaemia?

Hb>16.5g/dL in women and 18.5d/dL in men

red cell mass >25% above normal

JAK2 617V F mutation

18

What are the minor criteria for polycythaemia?

BM biopsy showing hypercellularity

low serum epo

endogenous erythroid colony in vitro

increased serum uric acid and vit b12 and vit b12 binding protein

19

What is the prognosis of polycythaemia without treatment?

6-18 months

20

Why is uric acid increased in polycythaemia?

increased RBC breakdown, increases uric acid

21

Treatment of secondary polycythaemia?

phlebotomy to maintain circulation and reduce viscosity

treat underlying condition

o2 for hypoxia, weight loss, smoking cessation, surgery to correct AV shunts

hydroxyurea

22

What is disseminated intravascular coagulation?

widespread inappropriate fibrin deposition within the vasculature from increased tissue factor

23

What are the causes of DIC?

infection - meningococcaemia, septicaemia, malaria, varicella, CMV, HIV
malignancy - AML, mucin secreting adenocarcinoma
obstetric complications - amniotic fluid embolus, retained placenta, septic abortion
anaphylaxis
trauma, burns
liver failure
pancreatitis
heat stroke, acute hypoxia, blood loss, snake venom

24

Pathophysiology behind DIC?

activation of the coagulation pathway in response to infection, this uses up platelets and coagulation factors so secondary activation of fibrinolysis leading to fibrin degradation products which inhibit fibrin polymerisation, and no platelets left for other clotting

25

Clinical features of DIC?

acutely ill, shock, can be no bleeding or widespread haemorrhage, bleeding from mouth, nose, venepuncture

26

Where in the body is mainly affected by DIC?

skin, brain and kidneys

27

What will investigations show in severe DIC?

prolonged PT, APPT, TT
low fibrinogen level
high FDPs and D dimer due to intense fibrinolytic activity, stimulated by the prescence of fibrin
severe thrombocytopaenia
blood film shows fragmented RBC

28

What will investigations show in mild DIC?

without bleeding
raised FDPs
increased synthesis of coagulation factors and platelets
normal PT, APTT, TT and platelets

29

What is the treatment of DIC?

transfusion of platelet concentrates, FFP, cryoprecipitate and RBCs if bleeding
activated protein c concentrates
NO inhibitors of fibrinolysis as may cause fibrin deposition

30

Complications of DIC?

gangrene from thrombosis