Haematology Flashcards
What is the pathology behind transfusion-associated graft vs host disease? Who is at an increased risk?
T-cells in blood products attack the recipient’s tissues.
Increased risk pts include immunosuppressed or previous Hodgkin’s lymphoma.
What is Transfusion associated circulatory overload (TACO)?
Pulmonary oedema due to circulatory excess, occurs in those who cannot cope with the excess fluid after blood transfusion (elderly, young, heart failure).
How can you mitigate the risk of transfusion associated circulatory overload?
Prophylactic furosemide to those at higher risk (elderly, children, heart failure). Also ensure to only give them 1 unit at a time.
What is transfusion associated lung injury (TRALI)?
Non-cardiogenic pulmonary oedema and ARDS as a result in activation of immune cells in the lungs.
Which factors are assessed by the APTTR and the INR?
APTTR: 8, 9, 11,12
INR: 10, 9, 7, 2
What is the ISTH BAT score?
ISTH ‘bleeding assessment score’ for assessing the severity of potential bleeding disorders.
>3 men and >5 women is abnormal.
What is a mixing study?
Mixing pt plasma with normal plasma (50:50) to see if a problem is corrected.
If it is just a deficiency it will completely correct the problem.
If it is autoimmune due to autoantibody destruction then it won’t correct as the antibodies would destroy it in normal blood too.
What is DIC? What are the lab findings?
Loads of small clots throughout the body meaning clotting factors are used up and the pt is at a significantly increased risk of bleeding.
Secondary to infection, injury, and malignancy.
Labs: elevated D-dimer, increased APTT and PT, low platelets and fibrinogen.
What is HUS? What is it most commonly caused by?
Haemolytic uremic syndrome: haemolytic anaemia (schistocytes), thrombocytopenia (bleeding/bruising), AKI.
Typically caused by diarrhoeal/foodborne illness (E.coli 0157) when they break down and release toxins.
What is Atypical HUS?
Caused by complement deficiencies rather than infection.
What causes intravascular haemolysis?
Something within the vessels causing RBCs to become shredded/fragmented (schistocytes). E.g., mechanical heart valve and the fibrin clots in DIC.
What blood results might indicate an intravascular haemolysis?
Schistocytes and reticulocytes on blood film.
Raised bilirubin and LDH, haemoglobinuria (due to free Hb in urine), decreased haptoglobin.
How do you manage a febrile non-haemolytic transfusion reaction?
Stop transfusion, give paracetamol (anti-pyretic), and recommence at a slower rate once stable.
What are the signs of essential thrombocytosis? What is it caused by?
Dizziness, bleeding (including melena), thrombocytosis, raised platelets, headaches, splenomegaly, erythromelalgia (burning, red, hot skin), livedo reticularis (nettle reddish blue pattern on skin).
Caused by JAK2 V617F mutation.
What is the inheritance pattern of sickle cell anaemia? How can it be diagnosed?
- Autosomal recessive
- A-haemoglobin electrophoresis shows sickling of cells and genetic testing will identify allele
What are the 4 main Crises that someone with sickle cell may present with?
- Aplastic crisis: profound anaemia, likely shows pancytopenia, caused by infections. present with tachycardia and tachypnoea in absence of splenomegaly.
- Acute sequestration crisis: excessive blood trapped in spleen causes reduction in circulating volume.
- Vaso-occlusive crisis: microvascular obstruction due to sickling, inflammation, and vasoconstriction. Cold, dehydrated, and after exercise trigger this. Very painful.
- Chest crisis: presents with tachypnoea, wheeze, and cough, with hypoxia and pulmonary infiltrates on chest X-ray. Unknown cause.
Why do sickle cell pts experience hyposplenism? What is the consequence of this?
Repeated splenic infarctions which can cause reduced splenic function.
Increased susceptibility to encapsulated organisms ie, pseudomonas aeruginosa, haemophilus influenza, strep pneumoniae, etc.
A sickle cell pt with >3 painful crisis in 12 months may indicate the need for what medication? How does it work?
Hydroxyurea - increases foetal Hb (has no beta subunit so not susceptible to sickling).
What is the inheritance pattern for Hereditary Haemorrhagic Telangiectasia (Osler-Weber-Rendu syndrome)? What are the complications?
Autosomal dominant ENG and ACVRL1 genes.
Recurrent epistaxis (malformations in nasal mucosa), widespread telangiectasia, AVM malformations.
What is the most common hereditary thrombophilia? What is its inheritance pattern?
Factor V Leiden mutation.
Autosomal dominant.
Why does a Factor V Leiden mutation increase the risk of thromboembolic disease?
Factor V is resistant to degradation by Protein C, increasing thrombin formation and creating a prothrombotic state.
What is the inheritance pattern for G6PD deficiency? What is it?
X-linked.
G6PD (glucose-6 phosphate dehydrogenase) deficiency is an enzyme deficiency increasing susceptibility to the development of haemolytic anaemia.
What are the common triggers of haemolysis in G6PD deficiency pts?
Medications- sulphonylureas, ciprofloxacin, nitrofurantoin.
How might someone in a haemolytic crisis with a background of G6PD deficiency present?
SOB, exhaustion, recent hx of starting a new medication, dark urine, scleral ictus, blood smears showing RBC fragments, bite cells (misshaped RBCs) and heinz bodies (denatured Hb).
What is the inheritance pattern for congenital sideroblastic anaemia? What is it?
X-lined recessive (predominantly affecting males)
Defect in haem synthesis .
What type of anaemia is seen in congenital sideroblastic anaemia?
Microcytic anaemia but normal iron levels.
Inefficient erythropoiesis means the iron isn’t used and becomes deposited in mitochondria and various organs.
What is seen on bone marrow aspiration for congenital sideroblastic anaemia? What do you see on blood film?
BM - Ring sideroblasts (abnormal RBCs).
BF - pappenheimer bodies (basophilic granules of iron).
How may congenital sideroblastic anaemia present?
Fatigue, dyspnoea, palpitations, microcytic anaemia, hepatosplenomegaly.
