Haem Flashcards
List some examples of extra-vascular haemolysis.
Autoimmune haemolytic anaemia
Hereditary spherocytosis
List some examples of intra-vascular haemolysis.
Malaria
G6PD deficiency
Pyruvate kinase deficiency
Mismatched blood transfusion
MAHA
Paroxysmal nocturnal haemoglobinuria
What is the most common cause of intravascular haemolysis worldwide?
Malaria
List some consequences of haemolytic anaemia.
Anaemia
Erythroid hyperplasia
Increased folate demand
Susceptibility to parvovirus B19 infection
Propensity to gallstones
Increased risk of iron overload
Increased risk of osteoporosis
Why is parvovirus B19 infection dangerous in patients with haemolytic anaemia?
It infects erythroid cells in the bone marrow and arrests their maturation
If this happens in someone with shortened red cell survival, it can cause a dramatic drop in Hb (aplastic crisis)
NOTE: this can be identified by observing a low reticulocyte count
Why do people with haemolytic anaemia have an increased risk of developing gallstones?
Increased generation of bilirubin
List some laboratory features of haemolytic anaemia.
Anaemia
Increased reticulocytes
Polychromasia
Increased LDH
Increased bilirubin
Reduced/absent haptoglobins
Haemoglobinuria
Haemosiderinuria
What is polychromasia?
Red cells take up both eosinophilic and basophilic dye giving them a bluish appearance – this is due to the presence of reticulocytes
What is increased LDH a marker of?
LDH is an enzyme found in high concentrations within red cells
Increased LDH suggests intravascular haemolysis
What are haptoglobins? What is the significance of reduced haptoglobins?
Haptoglobins are proteins in the bloodstream that bind to and remove free haemoglobin from the bloodstream
Low haptoglobins suggests that there is a lot of free haemoglobin in the bloodstream
Which stains are used for haemosiderinaemia?
Perl’s stain
Prussian blue stain
What does the presence of haemoglobinuria and haemosiderinaemia imply?
Intravascular haemolysis
Describe the inheritance of hereditary spherocytosis.
75% family history (autosomal dominant)
25% de novo mutations
What is the hall mark of red cells in hereditary spherocytosis?
Osmotic fragility – red cells show increases sensitivity to lysis in hypotonic saline
What is another test for hereditary spherocytosis?
Reduced binding to eosin 5-maleimide (dye)
This is shown by flow cytometry
Describe the appearance of the blood film in hereditary spherocytosis.
The cells lack a central area of pallor because they have lost the biconcave shape
The cells are small and more densely stained
There may be polychromatic cells (due to the presence of a young red cell population)
Outline the blood film and FBC features of eliptocytosis.
The red cells are elliptical but there is no polychromasia and the blood count is likely to be normal because there is little haemolysis
Describe the inheritance pattern of G6PD deficiency.
X-linked recessive
List some triggers for haemolysis in G6PD deficiency.
Drugs (antimalarials, antibiotics, dapsone, vitamin K)
Infections
Fava beans
Naphthalene mothballs
Describe the appearance of the blood film in G6PD deficiency during acute haemolysis.
Contracted cells
Nucleated red cells
Bite cells
Hemighosts (Hb retracted to one side of the cell)
What is a Heinz body? What is it suggestive of?
Denatured haemoglobin
Suggestive of oxidative haemolysis
Which stain is used to look for Heinz bodies?
Methylviolet
What is a characteristic blood film feature of pyruvate kinase deficiency?
Echinocytes – red cells with a lot of short projections
What is a characteristic blood film feature of pyrimidine 5-nucleotidase deficiency?
Basophilic stippling
NOTE: this is also seen in lead poisoning because lead inhibits pyrimidine 5-nucleotidase
What are Ham’s test and flow cytometry for GPI-linked proteins used for?
Paroxysmal nocturnal haemoglobinuria
NOTE: Ham’s test looks at the sensitivity of red cells to lysis by acidified serum
Outline the principles of management of haemolytic anaemia.
Folic acid supplementation
Avoidance of triggers in G6PD deficiency
Blood transfusions/exchange
Immunisations against blood-borne viruses
Monitor for chronic complications (e.g. gallstones)
Splenectomy if needed
List some indications for splenectomy related to haemolytic anaemia.
Pyruvate kinase deficiency
Hereditary spherocytosis
Severe eliptocytosis/pyropoikilocytosis
Thalassemia syndromes
Autoimmune haemolytic anaemia
What is the main risk of splenectomy?
Overwhelming sepsis due to susceptibility to capsulated bacteria (e.g. pneumococcus)
NOTE: risk can be reduced by using penicillin prophylaxis and immunisations
List some specific criteria for splenectomy.
Transfusion dependence
Growth delay
Physical limitation
Hypersplenism (where it causes pooling and physical symptoms)
Age > 3 years and < 10 years
Which cell level does CML tend to occur in?
Pluripotent haematopoietic stem cell
Which cell level does AML tend to occur in?
Pluripotent haematopoietic stem cell or multipotent myeloid stem cell
Which chromosomal duplications are most commonly associated with AML?
8 and 21 (there is a predisposition seen in Down syndrome)
Which chromosomal aberration causes APML?
Translocation 15;17
What is a characteristic feature of APML? Why does this occur?
Haemorrhage – this is because APML is associated with DIC and hyperactive fibrinolysis
In what way are the promyelocytes in APML considered ‘abnormal’?
They contain multiple Auer rods
Describe how the variant version of APML is different from the original version.
The variant form has granules that are below the resolution of a light microscope
They also tend to have bilobed nuclei
Which microscopic feature is pathognomonic of myeloid leukaemias?
Auer rods
Which stain can be used to distinguish myeloid leukaemias from other leukaemias?
Myeloperoxidase, sudan black, non-specific esterase
List the clinical features of AML.
Bone marrow failure (anaemia, neutropaenia, thrombocytopaenia)
Local infiltration (splenomegaly, hepatomegaly, gum infiltration, lymphadenopathy, CNS, skin)
Hyperviscosity if WBC is very high (can cause retinal haemorrhages and exudates)
Outline the tests that may be used to diagnose AML.
Blood film
Bone marrow aspirate
Cytogenetic studies (done in EVERY patient)
Molecular studies and FISH
Outline the supportive care given for AML.
Red cells
Platelets
FFC/cryoprecipitate in DIC
Antibiotics
Allopurinol (prevent gout)
Fluid and electrolyte balance
Chemotherapy
List some determinants of prognosis in AML.
List some determinants of prognosis in AML.
What are the four phases of chemotherapy for ALL?
Remission induction
Consolidation and CNS therapy
Intensification
Maintenance
List some investigations used in the diagnosis of ALL.
FBC and blood film
Bone marrow aspirate
Immunophenotyping
Cytogenetic/molecular analysis
How long does chemotherapy for ALL usually take? Why is it longer in boys?
2-3 years
Longer in boys because the testes are a site of accumulation of lymphoblasts
Outline the supportive care for ALL.
Blood products
Antibiotics
General medical care (central line, gout management, hyperkalaemia management, sometimes dialysis)
List some pro-coagulant factors in the body.
Platelets
Endothelium
vWF
Coagulation cascade
List some anti-coagulant factors in the body.
Fibrinolysis
Anti-thrombins
Protein C/S
Tissue factor pathway inhibitor
What is the life span of platelets?
10 days
NOTE: this is important because it means that the effect of antiplatelet drugs lasts for 10 days after stopping the drug
What are the two ways in which platelets can adhere to sub-endothelial structures?
DIRECTLY – via GlpIa
INDIRECTLY – via binding of GlpIb to vWF (this is MORE IMPORTANT)
Which factors, released by platelets after adhesion, promote platelet aggregation?
Thromboxane A2
ADP
Describe the effects of aspirin and other NSAIDs on the arachidonic acid pathway.
Aspirin is an irreversible COX inhibitor
Other NSAIDs reversibly inhibit COX
What is the rate-limiting step for fibrin formation?
Factor 10a
What are the effects of thrombin?
Activates fibrinogen
Activates platelets
Activates profactors (factor 5 and 8)
Activates zymogens (factor 7, 11 and 13)
Name the complex that is responsible for activating prothrombin to thrombin.
Prothrombinase complex
What is required for adequate production/absorption of vitamin K?
Bacteria in the gut produce vitamin K
It is fat-soluble so bile is needed for vitamin K to be absorbed
What is the most common cause of vitamin K deficiency?
Warfarin
Name two factors that convert plasminogen to plasmin.
Tissue plasminogen activator
Urokinase
Name two factors that directly inhibit plasmin.
Alpha-2 antiplasmin
Alpha-2 macroglobulin
What is the role of thrombin-activatable fibrinolysis inhibitor (TAFI)?
Inhibitor of fibrin breakdown
Describe the action of antithrombins.
Bind to thrombin in a 1:1 ratio and this complex is excreted in the urine
How many types of antithrombin are there?
Five (antithrombin-III is the most active)
What is the most thrombogenic hereditary condition?
Antithrombin deficiency
Why does Factor V Leiden cause a prothrombotic state?
The factor 5a will be resistant to breakdown by protein C
What is the role of tissue factor pathway inhibitor?
TFPI neutralises the tissue factor-factor 7a complex once it has initiated the clotting cascade
List some genetic defects that cause excessive bleeding.
Platelet abnormalities
Vessel wall abnormalities
Clotting factor deficiencies
Excess clot breakdown
List some acquired defects that cause excessive bleeding.
Liver disease
Vitamin K deficiency
Autoimmune diseases (platelet destruction)
Trauma
Anti-coagulants/anti-platelets
What is the difference between immediate and delayed bleeding with regards to the underlying pathological process?
Immediate – issue with the primary haemostatic plug (platelets, endothelium, vWF)
Delayed – issue with the coagulation cascade
Describe the key clinical differences between platelet disorders and coagulation factor disorders.
Platelet disord
· Bleeding from skin and mucous membranes
· Petechiae
· Small, superficial ecchymoses
· Bleeding after cuts and scratches
· Bleeding immediately after surgery/trauma
· Usually mild
Coagulation factor disorders
· Bleeding into soft tissues, joints and muscles
· No Petechiae
· Large, deep ecchymoses
· Haemarthroses
· No bleeding from cuts and scratches
· Delayed bleeding from surgery or trauma
· Often SEVERE
What can cause immune-mediated thrombocytopaenia?
Idiopathic
Drug-induced (e.g. quinine, rifampicin)
Connective tissue disorder (e.g. SLE)
Lymphoproliferative disease
Sarcoidosis
List two non-immune mediated conditions that cause thrombocytopaenia.
DIC
MAHA
What are the main differences between acute and chronic ITP?
Acute
· Mainly children
· Usually there is a preceding infection
· Abrupt onset of symptoms
· Lasts 2-6 weeks
· Spontaneously resolves
Chronic
· Mainly occurs in adults
· More common in females
· Can be abrupt or indolent
· Does not resolve spontaneously
How is ITP treated?
Mainly with steroids and IVIG based on the platelet count
Give some examples of causes of thrombocytopaenia that can be diagnosed by blood film.
Vitamin B12 deficiency
Acute leukaemia
What clotting study abnormality would be seen in Haemophilia?
Prolonged APTT
Outline the clinical features of haemophilia.
Haemarthroses (MOST COMMON)
Soft tissue haematomas (e.g. shortened tendons, muscle atrophy)
Prolonged bleeding after surgery/dental extractions
NOTE: haemophilia A and B are clinically indistinguishable
What is a typical lesion seen in coagulation factor disorders?
Ecchymoses
What is the most common coagulation disorder? What is its inheritance pattern?
Von Willebrand disease
Autosomal dominant – type 1 and 2
Autosomal recessive – type 3
What is the main clinical feature in von Willebrand disease?
Mucocutaneous bleeding
Outline the classification of von Willebrand disease.
Type 1 – partial quantitative deficiency
Type 2 – qualitative deficiency
Type 3 – complete quantitative deficiency
Describe the expected laboratory test results for the three types of von Willebrand disease.
Type 1 – low antigen, low activity, normal multimer
Type 2 – normal antigen, low activity, normal multimer
Type 3 – very low antigen, very low activity, absent multimer
Name a source of vitamin K.
Green vegetables
Vitamin K is synthesised by intestinal flora
List some causes of DIC.
Sepsis (MOST COMMON)
Trauma (e.g. fat embolism)
Obstetric complications (e.g. amniotic fluid embolism)
Malignancy
Vascular disorders
Reaction to toxin
Immunological (e.g. transplant rejection)
Describe the typical clotting study results in DIC.
Prolonged APTT and PT
Prolonged TT
Decreased fibrinogen
Increased FDP
Decreased platelets
Schistocytes (due to shearing of red blood cells as it passes through a fibrin mesh)
Outline the treatment of DIC.
Treat underlying disorder
Anticoagulation with heparin
Platelet transfusion
FFP
Coagulation inhibitor concentrate
What are Janus Kinases?
A family of four tyrosine kinase receptors associated with haemopoietic cell growth factor receptors
What is a chronic myeloproliferative disorder?
A group of clonal disorders of haemopoietic stem cells characterised by the overproduction of one or more mature myeloid cellular elements in the blood
There is a trend towards increased fibrosis in the bone marrow
Some cases will develop into acute leukaemia
Outline the usual presentation of myeloproliferative disorders.
Preponderance to thrombosis
Splenomegaly
Haemorrhage
List some chronic myeloproliferative disorders.
Polycythaemia vera
Essential thrombocythaemia
Idiopathic myelofibrosis
Idiopathic erythrocytosis
Chronic granulocytic leukaemia
Describe the clinical presentation of polycythaemia vera.
Incidental finding
Symptoms of hyperviscosity (headaches, visual disturbances, fatigue, dyspnoea)
Increased histamine release (Aquagenic pruritus, peptic ulceration)
Splenomegaly
Plethora
Erythromelalgia (red painful extremities)
Thrombosis
Retinal vein engorgement
Gout
Describe the appearance of a bone marrow biopsy in polycythaemia vera.
Increased cellularity (mainly erythroid cells)
Slight reticulin fibrosis and megakaryocyte abnormalities
What investigation finding is considered diagnostic of polycythaemia vera?
Presence of JAK 2 V617F mutation
Which other JAK mutation is a significant finding and which condition is it associated with?
Exon 12 mutation
It is associated with idiopathic erythrocytosis
What are some causes of JAK 2 V617F negative polycythaemia?
Pseudopolycythaemia
True polycythaemia that is secondary to increased EPO (e.g. hypoxia, renal disease, tumours)
What is idiopathic erythrocytosis?
Isolated erythrocytosis with low EPO
Treated with venesection only
NO JAK 2 V617F mutation, but some cases will have an exon 12 mutation
Outline the prognosis of idiopathic erythrocytosis and polycythaemia vera.
Idiopathic erythrocytosis – no adverse prognosis if Hct is maintained
Polycythaemia vera – most survive 10 years, causes of death include thrombosis, leukaemia and myelofibrosis
What is essential thrombocythaemia?
Myeloproliferative disorder mainly involving the megakaryocyte lineage (platelet count > 600 x 109/L)
What proportion of essential thrombocythaemia patients have JAK 2 mutations?
50%
Outline the treatment options for essential thrombocythaemia.
Aspirin
Anagrelide (specific inhibitor of platelet formation – may accelerate myelofibrosis)
Hydroxycarbamide (MAIN TREATMENT – may be leukaemogenic)
Alpha-interferon (may be used in patients < 40 years)
Describe the prognosis of essential thrombocythaemia.
Normal life span
Leukaemic transformation in about 5% of patients after 10 years
Myelofibrosis is uncommon
Define chronic idiopathic myelofibrosis.
A clonal myeloproliferative disease with proliferation mainly of megakaryocytes and granulocytic cells, associated with reactive bone marrow fibrosis and extramedullary haemopoiesis
Describe the typical clinical presentation of myelofibrosis.
Incidental finding
Cytopaenias
Thrombocytosis
Splenomegaly (can be MASSIVE)
Hepatomegaly
FLAWS
Gout
Describe the two stages of myelofibrosis.
Pre-fibrotic = blood changes are mild with hypercellular marrow
Fibrotic = splenomegaly, blood changes, dry tap, prominent fibrosis and later osteosclerosis
Describe the appearance of myelofibrosis on a blood film.
Leukoerythroblastic picture
Tear drop poikilocytes
What are some features of the bone marrow in myelofibrosis?
Dry tap
Trephine biopsy will show increased reticulin or collagen fibrosis, prominent megakaryocyte hyperplasia and new bone formation
Outline the treatment options for myelofibrosis.
Symptomatic treatment (e.g. transfusions for anaemia)
Splenectomy
Cytoreductive therapy (hydroxycarbamide and thalidomide)
Bone marrow transplant (in younger patients)
Describe the prognosis of myelofibrosis.
Median 3-5 year survival
Which types of cancer are associated with causing secondary polycythaemia?
Renal cell carcinoma
Liver cancer
Due to the production of EPO
What are the typical laboratory findings of iron deficiency anaemia?
Low ferritin
Low transferrin saturation
High TIBC
What is leucoerythroblastic anaemia?
Anaemia characterised by the presence of red and white cell precursors
What are the morphological features of leucoerythroblastic anaemia seen on blood film?
Tear drop red blood cells (aniso- and poikilocytosis)
Nucleated RBCs
Immature myeloid cells
What does leucoerythroblastic anaemia tend to be caused by?
Bone marrow infiltration (leukaemia, lymphoma, myeloma, solid tumours, myelofibrosis, military TB, severe fungal infection)
Which test distinguishes immune-mediated and non-immune mediated haemolytic anaemia?
DAT or Coombs’ test
DAT +ve means that the haemolytic anaemia is mediated through immune destruction of red cells
What morphological change is seen on the blood film of patients with autoimmune haemolytic anaemia?
Spherocytes
List some causes of non-immune haemolytic anaemia.
Infection (e.g. malaria)
Microangiopathic haemolytic anaemia (MAHA)
List some key features of MAHA.
Usually caused by underlying adenocarcinoma
Red cell fragments
Low platelets
DIC/bleeding
Outline the mechanism of MAHA.
An underlying adenocarcinoma produces procoagulant cytokines that activate the coagulation cascade
This leads to DIC and the formation of fibrin strands in various parts of the microvasculature
Red cells will be pushed through these fibrin strands and fragment
NOTE: always consider underlying adenocarcinoma in any patient presenting with MAHA
What is the main difference seen in the blood film of patients with acute and chronic leukaemia?
Chronic – mature white cells are raised
Acute – immature blast cells are raised
List some causes of neutrophilia.
Corticosteroids (due to demargination)
Underlying neoplasia
Tissue inflammation (e.g. colitis, pancreatitis)
Myeloproliferative/leukaemia disorder
Infection
List some infections that characteristically do not cause neutrophilia.
Brucella
Typhoid
Many viral diseases
List some key features of a reactive neutrophilia on a blood film.
Band cells (presence of immature neutrophils (band cells) show that the bone marrow has been signalled to release more WBCs)
Toxic granulation
Clinical signs of infection/inflammation
What are some key blood film and clinical features suggestive of a myeloproliferative disorder?
Neutrophilia
Basophilia
Immature myelocytes
Splenomegaly
NOTE: you may see raised Hb and raised platelets in CML if it affects those lineages
What are some key blood film features suggestive of AML?
Neutrophilia
Myeloblasts
List some causes of monocytosis.
Bacteria: TB, Brucella, typhoid
Viral: CMV, VZV
Sarcoidosis
Chronic myelomonocytic leukaemia
List some causes of reactive eosinophilia.
Parasitic infection
Allergy (e.g. asthma, rheumatoid arthritis)
Underlying neoplasms (e.g. Hodgkin’s lymphoma, T cell lymphoma, NHL)
Drug reaction (e.g. erythema multiforme)
Which gene mutation causes chronic eosinophilic leukaemia?
FIP1L1-PDGFRa fusion gene
Which type of virus typically causes basophilia?
Pox viruses
List some causes of reactive lymphocytosis.
Infection (EBV, CMV, toxoplasmosis, rubella, HSV)
Autoimmune diseases (NOTE: these are more likely to cause lymphopaenia)
Sarcoidosis
How would the lymphocytes seen on a blood film due to a viral infection be different from leukaemia/lymphoma?
Viral infection: reactive or atypical lymphocytes (EBV)
CLL or NHL: small lymphocytes and smear cells
What is light chain restriction?
An individual B cell will either express kappa or lambda light chains (not both)
In response to an infection, you will get a polyclonal B cell response so there will be a roughly even mixture of kappa and lambda light chains
In lymphoproliferative disorders, monoclonal proliferation of a B cell expressing only one type of light chain (e.g. kappa) will mean that the proportion of kappa relative to lambda will increase (e.g. showing an overwhelming majority of kappa)
What percentage of hospital deaths are caused by PE?
5-10%
List some anticoagulant molecules produced by the endothelium.
Thrombomodulin
Endothelial protein C receptor
Tissue factor pathway inhibitor
Heparans
NOTE: it does not normally produce tissue factor
Which antiplatelet factors are produced by the endothelium?
NO
Prostacyclin
What is the mechanism of action of heparin?
Increases anticoagulant activity by potentiating anti-thrombin III
How is unfractionated heparin monitored?
It has variable pharmacokinetics and a variable dose-response
Must be monitored with APTT or anti-Xa levels
How can the action of warfarin be reversed?
Administering vitamin K – takes 12 hours
Giving factors 2, 7, 9 and 10 – immediate
What is the antidote for heparin?
Protamine
Describe the gender difference regarding the risk of recurrent of VTE.
Men have a greater risk of recurrence
NOTE: proximal thrombosis has a higher rate of recurrence than distal thrombosis
What should all patients > 60 years old with idiopathic thromboembolic disease be offered?
CT scan to check for an underlying cause
Define myelodysplastic syndrome.
Biologically heterogenous group of acquired haematological stem cell disorders. elderly pts
What are the key characteristics of myelodysplastic syndromes?
Development of a clone of marrow stem cell with abnormal maturation resulting in functionally defective blood cells and a reduction in cell counts
This leads to cytopaenia, functional abnormalities of cell maturation and an increased risk of transformation to leukaemia
How do myelodysplastic syndromes typically present?
Symptoms/signs of bone marrow failure developing over weeks/months
List and describe some blood and bone marrow features of myelodysplastic syndromes.
Pelger-Huet anomaly (bilobed neutrophils)
Dysgranulopoiesis of neutr7ophils (failure of granulation)
Dyserythropoiesis of red blood cells (lack of separation between red cell precursors, presence of abnormal ring of cytoplasm around the nucleus of precursor red cells)
Dysplastic megakaryocytes (micro-megakaryocytes)
Increased proportion of blast cells in the bone marrow (normally < 5%)
What might you see if you stained for iron in the bone marrow of a patient with a myelodysplastic syndrome?
Ringed sideroblasts (accumulation of iron around the nuclei of red blood cell precursors)
What is the presence of myeloblasts with Auer rods suggestive of?
Acute myeloid leukaemia
List some factors that are taken into account when classifying types of myelodysplastic syndrome.
Cell lineage affected
Blast cell proportions
Cytogenetics
Presence of ringed sideroblasts
Cytopaenias
What are the five prognostic variables that are used to calculate prognostic risk using the Revised International Prognostic Scoring System (IPSS-R) for Myelodysplastic Syndromes?
Bone marrow blast percentage
Karyotype
Haemoglobin
Platelets
Neutrophils
NOTE: high risk is considered a score > 6, low risk < 1.5
What are the usual causes of death in patients with myelodysplasia?
1/3 infection
1/3 bleeding
1/3 leukaemia
What are the two treatments that can prolong life in myelodysplastic syndromes?
Allogeneic stem cell transplantation
Intensive chemotherapy
NOTE: as most MDS patients are elderly, they often cannot tolerate treatment
List some other treatments that may be used in myelodysplastic syndromes.
Supportive Care (blood products, antimicrobials, growth factors (e.g. EPO, GM-CSF))
Biological modifiers
· Immunosuppression
· Azacytidine (hypomethylating agent)
· Decitabine
· Lenalidomide (used in 5q minus syndrome)
Oral chemotherapy (e.g. hydroxyurea)
Low-dose chemotherapy (SC low-dose cytarabine)