Flashcards in Haematology Deck (446)
What is polycythaemia (erythrocytosis)?
an increase in Hb, PCV and RBC
What is absolute polycythaemia?
true increase in red cell volume, primary or secondary
What is relative or stress/spurious polycythaemia?
normal red cell volume, decreased plasma volume, can occur in dehydration and burns
Is Hb or PCV a better indicator for polycythaemia?
PCV, as Hb could be low during iron deficiency
What is a normal PCV in the blood?
Primary causes of polycythaemia?
polycythaemia rubra vera, epo receptor mutations, high oxygen affinity Hb
Secondary causes of polycythaemia?
increase in epo from hypoxia, smoking, high altitude, chronic lung disease, anoxia and tumour
What is polycythaemia rubra vera?
stem cell disorder with an alteration in the pluripotent progenitor cell, >95% in JAK2 mutations
What is the JAK2 gene?
a signal transducer, especially those triggered by haemopoetic growth factors
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
What complications can polycythaemia lead to?
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
How many polycythaemia cases develop into myelofibrosis or AML?
myelofibrosis in 30%
AML in 5%
What will investigations show in polycythaemia?
raised haematocrit, Hb, RCC, MCV, raised WCC and platelets, neutrophil leucocytosis, o2 sat >92%, thrombocytosis, splenomegaly,
What will bone marrow show in polycythaemia?
bone marrow hypercellular with prominent megakaryocutes, low epo
What is the WHO diagnostic criteria for polycythaemia?
2 major and 1 minor or main major and 2 minor
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
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
What is the prognosis of polycythaemia without treatment?
Why is uric acid increased in polycythaemia?
increased RBC breakdown, increases uric acid
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
What is disseminated intravascular coagulation?
widespread inappropriate fibrin deposition within the vasculature from increased tissue factor
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
heat stroke, acute hypoxia, blood loss, snake venom
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
Clinical features of DIC?
acutely ill, shock, can be no bleeding or widespread haemorrhage, bleeding from mouth, nose, venepuncture
Where in the body is mainly affected by DIC?
skin, brain and kidneys
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
blood film shows fragmented RBC
What will investigations show in mild DIC?
increased synthesis of coagulation factors and platelets
normal PT, APTT, TT and platelets
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