Week 3 Haematology Flashcards
Site of Haemopoiesis
Site: red marrow inside bone marrow of long bones
First few weeks of gestation: yolk sac
From 6 weeks to 6 months of feotal life: liver and spleen are main sites
After 6 months: bone marrow
In child and adult, bone marrow is only site:
- During childhood, marrow is replaced by fat.
- In adults, haemopoiesis only occurs in central skeleton and proximal ends of femur
Haemopoietic stem cell characteristics
Self renew
Unspecialised
Can differentiate
Rare (not many in bone marrow)
Quiescent (sometimes undergoes cell division)
Where are Haemopoietic stem cells found?
Bone marrow
Peripheral blood after G-CSF (granulocyte colony stimulating factor)
Umbilical cord
Haemopoietic stem cell fate
Self renew
Differentiate
Apoptosis
Stem cell fate influenced by micro-environmental signals (niche) and internal cues
Appreciate importance of bone marrow microenvironment
Bone marrow is composed of stromal cells and a microvascular network.
Stroma (bone marrow microenvironment) supports growth and development of stem cells
Stromal cells: macrophages, fibroblasts, fat cells, reticulum cells
- Display adhesion molecules to keep developing cells in bone marrow
- Supported by an extracellular matrix
- They secrete extracellular molecules e.g. collagen, fibronectin, proteoglycans
- Secrete adhesion molecules and growth factors
Bone marrow architecture: the stromal layer, the glycoproteins and extracellular matrix
Two types of bone marrow:
Red (erthrocytes) and yellow (fat cells)
Conditions that impair bone marrow function
Hereditary: Fanconi syndrome,. Sickle cell anaemia
Acquired: Leukaemia, Myelodysplasia Myeloproliferative disorders
Stages of leukaemogenesis (development of leukaemia)
Neoplastic cell is a haemopoietic stem cell, or early myeloid or lymphoid cell
The healthy haemopoietic stem cell is hit by event e.g. virus leading to mutations
This cell self renews and generate leukaemic cells
Leads to dysregulation of cell growth and differentiation
Develop basic understanding of clonal disorders of haemopoietic stem cells
Haematological malignancies and pre-malignant conditions are termed “clonal” if they arise from a single ancestral cell
Overproduction: Myeloproliferative disorders e.g. Polycythaemia rubra vera, Essential thrombocytosis
Abnormal stem cells: Leukaemia, Myelodysplasia e.g. refractory anaemia with excess blasts
Underproduction: Aplastic anaemia e.g. Fanconi’s anaemia
Myeloproliferative disorders
Clonal disorders of haemopoiesis leading to increased numbers of one or more mature blood progeny
- Can transform into acute myeloid leukaemia (cancer, which bone marrow makes abnormal myeloblasts)
- Associated with JAK2 and calreticulin mutation
Essential thromocytosis, polycythaemia ruba vera (too many red cells, myelofibrosis (BM filled with fibrous tissue)
Essential thrombocytosis: Overproduction of platelets (thrombocytes)
50% cases due to mutation of JAK2
50% cases due mutation of calreticulin mutation
Clinical features:
- Thrombotic or haemorrhagic complications (as platelets don’t clot, or clot too well)
- Splenomegaly
- Can become polycythaemia rubra vera (too many RBCs produced)
- leukaemic transformation in around 3%
Treatments:
Low risk group (under 40, no high risk features e.g. cardiac conditions, diabetes, previous thrombosis): aspirin or anti-platelet agent
Medium risk group (40-60, no high risk features): aspirin, hydroxycarbamide (low dose chemotherapy)
High risk group (over 60, or high risk feature): 1st line: Aspirin + hydroxycarbamide (ribonucleotide reductase inhibitor causing reduced deoxyribonucleotides)
2nd line: aspirin + anagrelide (inhibits megakaryocyte differentiation)
IFN-a: useful in managing ET in pregnancy
Bulsulphan, 32P (associated with increased risk of leukaemogenesis (development of leukaemia)
Jax2 inhibitor e.g. ruxolitinib (inhibits Jak1 and 2, 70% pts have reduced splenomegaly, functional improvement). However can cause thrombocytopenia (low platelets)
Abnormal cells produced: Myelodysplasia, leukaemia (example – Refractory anaemia with excess blasts)
Myelodysplastic syndromes:
Group of cancers characterised by dysplasia, ineffective haemopoiesis leading to cytopenias (impaired blood cell production)
- May have increased myeloblasts (normally lead to production of granulocytes)
- Associated with cytogenetic abnormalities e.g. trisomy 8
- Most characterised by bone marrow failure
Includes refractory anaemia with excess blasts and refractory anaemia with ring sideroblasts
High and low risk characterised by proportion of blast cells
Refractory anaemia with excess blasts:
- constitute 40% of MDS cases
- Multilineage dysplasia and increased myeloblasts
- Chance of progressing to acute myeloid leukaemia
Clinical features:
- fatigue, infections, bleeding (due to anaemia, neutropenia, thromobocytopenia)
- mostly elderly
- IPSS (international prognostic scoring system) based on:
- BM blasts
- Karyotype
- Cytopenias
Treatment: Blood and platelet transfusion
Iron chelation in younger pts
Growth factors - erythropoietin, G-CSF (granulocyte colony stimulating factor)
Low dose chemo e.g. Hydroxycarbamide
Demethylating agents e.g. azacytidine
Intensive chemo
Allogenic stem cell transplantation
Fanconi anaemia
Autosomal recessive inheritance
Bone marrow failure
20% of anaplastic anaemia cases (anaplastc anaemia - decreased haemopoietic stem cells in BM - leading to pancytopenia and low reticulocytes)
Characteristics:
- Bone marrow failure (so defective haemopoiesis)
- Short telomeres
- Malignancy (increased risk of AML)
Clinical features: Microphtalmia (small eyes), GI/GU malformations, Mental retardation
Fanconia anaemia mutations leads to alteration in DNA damage response (FA-BRCA pathway) leads to:
- abnormalities in MAPK, TNFa
- abnormal oxidative stress response
Leads to genomic instability, altered cell checkpoints and survival
Leads to formation of FA cancer cell
Main cause mortality is premature bone marrow failure
Gold standard therapy: allogenic stem cell transplant
Other treatments: Corticosteroids, androgens
Understand basic concepts of stem cell mobilisation and stem cell transplant
Autologous transplant: Patient’s own blood stem cells
Allogenic transplant: Donor’s blood stem cells
Types of donor:
Syngeneic Transplant - transplant between identical twins
Allogeneic sibling - HLA identical
Haplotype identical - half matched family member e.g. parent, half matched sibling
Volunteer unrelated (VUD)
Umbilical cord blood
Autologous transplant
- Collection - Pts receive Granulocyte colony stimulating factor +/- chemotherapy to make stem cells leave bone marrow so they can be collected
- Processing - Blood/bone marrow is processed to purify and concentrate stem cells
- Cryoperservation - Blood/bone marrow is frozen
- Chemotherapy - High dose chemo given to pt
- Reinfusion - Stem cells reinfused into patient
Can be used in pts with Hodgkin’s disease, non Hodgkins lymphoma, myeloma Almost all autografts use mobilised peripheral blood stem cells harvested by apheresis
Allogenic transplant
Peripheral blood stem cells, bone marrow, umbilical cord
Indications: acute and chronic leukaemias, relapsed lymphoma, aplastic anaemia
In malignant disease, has benefit of graft versus leukaemia effect as well as high dose chemo. However also has graft versus host disease.
Myeloablative regime: Pt has very high dose of chemo and high dose radiotherapy then transplant is given
Non myeloablative regime: Low-dose, less toxic regime. Provides immunosupressants to allow cells to engraft, but allows graft versus leukaemia to eradicate tumor
Donor lymphocyte infusion: T-cells from original bone marrow induces a graft versus leukaemia effect.
Prevents or treats relapse after SCT
High rate of graft versus host disease
Umbilical cord transplant:
Collected from umbilical cord and placenta
Advantages: more rapidly available than VUD (volunteer unrelated donor), less rigorous matching as immune system is naive
Disadvantages: small amount (adults need double transplant), slower engraftment, cannot use DLI if relapse occurs
Graft versus host disease
- Occurs in pts with allogenic transplant
- Donor’s immune system recognises host cells as foreign and attacks them -
Manifests as skin rash, jaundice or diarrhoea
2 forms: acute (occurs within 100 days of transplant) and chronic (occurs after 100 days of transplant)
GvHD treated with immunosuppressants e.g. cyclosporin
Graft versus leukaemia
Same cells which cause GvHD also attack leukaemia cells
GvL effective, especially in pts have been difficult to maintain remission
Minimising GvHD also minimises GvL thus causing increased risk of relapse
No GvHD in autologous transplant, so no GvL which causes increased risk in relapse
Problems in stem cell transplant
Limited donors available (upper age limit <65)
Mortality 10%-50%
GvHD
Immunosuppression required (1-2 years)
Infertility
Risk of cataract formation, hypothyroidism, osteoporosis
Relapse
To describe the requirements for normal red cell production
Erythropoietin Iron, B12, folate, minerals
Functioning bone marrow
Iron Transported by transferrin (glycoprotein made in liver) which transports iron to all tissues, erythroblasts, hepatocytes, muscle
- binding domains 30% saturated with Fe
- Iron ingested Fe3+ converted to Fe2+ by duodenal cytochrome B
- Iron enters enterocyte by divalent metal transporter type I
- Stored as ferritin
- Exits enterocyte through ferroportin (and hepcidin) Fe2+ converted to Fe3+
- Transported round body by binding to transferrin
- Old RBCs are removed by macrophages of RES
- Stored as ferritin in macrophages
- Hepcidin reduces levels of iron plasma.
Degrades ferroportin, reducing iron absorption and decreases release from RES.
Hereditary haemochromotosis - loss of hepcidin
Iron deficiency anaemia
Commonest anaemia in world
Gradual onset
Hypochromic and microcytic RBCs
Less iron ( and more transferrin produced to compensate)
- Low serum ferritin indicates low RES stores
Development of IDA
Latent iron deficiency: Serum ferritin: low, RES iron stores: low, Hb: normal
Serum ferritin: low, RES iron stores: low, Hb: low (IDA)
- Ferritin (acute phase protein) In presence of tissue inflammation (e.g. RA, IBD), IDA can occur with normal serum ferritin
Clinical features:
Koilonychia
Angular stomatitis
Atrophic Glossitis (pale, smooth, painless tongue)
Oesophageal web (Plummer vinson syndrome)
Causes:
Dietary
Blood loss
Malabsorption e.g. coeliac IDA in men and post menopausal women due to GI blood loss until proven otherwise
Treatment
Iron replacement: Ferrous sulphate
Ferrous gluconate IV iron (for oral intolerance, compliance, renal anaemia)
Anaemia of chronic disease
Failure of iron utilisation
Iron trapped in RES
Causes: Infection, Inflammation (kidney disease, rheumatologic, autoimmunity), Neoplasia
Anaemia of CRF (chronic renal failure) = ACD + low EPO
Lab values: Normochromic/normocytic or hypochromic/hypocytic
ESR (non specific marker for inflammation): increased
Ferritin: N or increased
Iron: low
TIBC (total iron binding capacity): low
When ESR raised, can show RBC roleaux (aggregrations)
Causes: - RES iron blockade, iron trapped in macrophages and not getting to erythrocytes, raised levels hepcidin
- Reduced EPO response
- Depressed marrow activity e.g. cytokine marrow depression
Treatment: Treat underlying disorder
B12/Folate
Essential for DNA synthesis and nuclear maturation
Required for all dividing cells, deficiency noted first in RBCs
Deficiency causes megaloblastic anaemia
B12
Dietary sources: Meat, dairy products
Absorption: B12 ingested
Gatsric parietal cells produce intrinsic factor
Intrinsic factor binds to B12
Intrinsic factor-B12 complex binds to cubulin (specific receptor in ileum)
B12 absorbed in blood and binds to transcobalamin
Stores: 3-4 years
Folate
Dietary sources: green veg
Absorption in SI
Stores: few days only
- Lack of B12 can lead to folate deficiency due to “methyl trap”
Lack of B12 leads to lack of methionine production.
- Leads to disparity in rate of synthesis of DNA precursors
- Leads to fragile DNA, abnormal cell division
- Ineffective erythropoiesis
- death of mature cells still in marrow
- Raised billirubin, raised LDH
- Affects all rapidly growing, DNA synthesising cells esp. bone marrow, epithelial surfaces - mouth, stomach, small intestine
Clinical features: - Megaloblastic anaemia (abnormal, immature precursors of RBCs), jaundice (raised bilirubin), CNS symptoms, demyelination SC tracts
- Neural tube defects in fetus
Symptoms and signs:
- Tired (macrocytic/megaloblastic anaemia)
- Easy bruising
- Mild jaundice “lemon yellow tint” (raised bilirubin)
- Neurological problems e.g. subacute combined degeneration of SC (due to B12 deficiency)
Causes of B12 deficiency:
- Dietary - no B12 intake
- Pernicious anaemia (auto immune condition - antibodies target gastric parietal cells so intrinsic factor not produced)
- Problem in terminal ileum e.g. Chron’s, resection
Causes of folate deficiency:
- Dietary
- Extensive small bowel disease e.g. Chron’s
- Increased cell turnover e.g. pregnancy
Causes of macrocytosis
B12/folate deficiency
Reticulocytosis
Cell wall abnormality e.g. alcohol, liver disease, hypothyroidism
With anaemia: bone marrow failure syndromes
Haemolytic anaemia
Anaemia related to reduced RBC lifespan
No blood loss or haematinic deficiency
Haematology:
20-100d: Hb normal, increased reticulocytes, increased UB (compensated haemolytic state)
<20d: decreaed Hb, increased reticulocytes, increased UB, splenomegaly (haemolytic anaemia)
2 types:
Congenital haemolytic anaemia
Acquired haemolytic anaemia
Abnormal RBC destruction: Intravasuclar vs Extravascular haemolysis
Intravasuclar haemolysis: destruction in general circulation
- mechanical trauma to red cell (red cell fragmentation syndromes
- ABO incompatible transfusion
- malaria
- cold IgM autoantibodies (cold autoantibodies cause RBCs to aggluitnate to blood film)
Lab findings:
Anaemia, reticulocytosis, raised UB
Haemoglobinuria (due to excess Hb in plasma filtered at glomerulus)
Haemosiderinuria (Hb broken down in haemosiderin which appears in urine)
Extravascular: destruction in RES system of spleen, liver, BM
- Warm (incomplete) antibodies (IgG). IgG attaches to red cell antigen and damages RBC membrane. Becomes spherocytic and phagocytosed by RES, esp. spleen, causing it to enlarge.
- Positive direct antiglobulin test detects presence of antibodies on RBC surface
Acquired haemolytic anaemia
-
Autoimmnune
- Warm type (IgG)
- Cold type (IgM) - Isoimmune (antibodies from something else .e.g mother) - haemolytic disease of newborn
- Non-immune - fragmentation haemolysis
Cold AIHA (autoimmune haemolytic anaemia)
IgM autoantibodies bind to RBC membrane, leading to its destruction
Causes:
Primary (idiopathic)
Secondary: Mycoplasma pneumoniae, infectious mononucleosis (glandular fever), lymphoproliferative disorders
Clinical features:
painful fingers/toes assoc with cold exposure
Treatment:
Mycoplasma - self limiting
Keep warm
Warm AIHA (autoimmune haemolytic anaemia)
Autoantibody IgG attaches to RBC membrane, causing destruction.
Damaged RBCs become spherocytic (RBCs round, rather than biconcave, no central pallor, smaller) and polychromatic. Phagocytosed by RES, esp. spleen, causing enlargement
Causes:
Idiopathic
Lymphoproliferative disorders - CLL, Non Hodgkin’s lymphoma
Drugs e.g. cephalosporins
SLE
Management:
Corticosteroids - Prednisolone
Folic acid
Blood transfusion
Splenectomy
Risks of splenectomy: increase risk of Strep. pneumoniae, Haemophilus Influenzae, Neisseria Meningitidis causing overwhelming post splenectomy infections
- Penicillin prophylaxis required
Direct Coombs Test
Detects antibody on RBC surface
Anti-IgG added to patient’s RBCs
Agglutination occurs, if there are RBCs are coated with IgG antibodies, present
Postive - AIHA, HDN (haemolytic disease of newborn. IgG antibodies produced by mother, target antigens on RBCs of fetus)
Indirect Coombs Test
Detect antibodies in serum
Anti-IgG and test RBCs mixed with pt’s serum. Agglutination occurs if serum antibodies present
Blood transfusion - antibody screening, cross-matching
Myelofibrosis
Myeloproliferative disorder
BM filled with fibrous tissue
Congenital haemolytic anaemia
1. Abnormalities of RBC membrane
Hereditary spherocytosis
- AD, RBCs are spherocytic and polychromatic (increased reticulocytes)
Jaundice
Splenomegaly
2. Haemoglobinopathies
3. Abnormalities in RBC enzymes
Pyruvate kianse deficiency anaemia
- AR, extravasuclar haemolysis, ATP depletion
Glucose 6 phosphate dehydrogenase deficiency:
- X-linked recessive, acute episodic intravascular haemolysis
- acute haemolysis from oxidative stress e.g. drugs - anti-malarials
Causes of Microcytic and Hypchromic RBCs
IDA
Thalassaemia
ACD
Siderblastic anaemia
Haemoglobinopathies
Inherited conditions where there is a lack of globin chains due to absent genes (thalassaemias) or abnormal globin chain (sickle cell)
Normal Hb production
Globin chains produced on ribosomes
Adult Hb (HbA) made up of 2 alpha and 2 beta chains
- 4 alpha globin genes (chromosome 16) and 2 beta globin genes (chromosome 11)
Feotal Hb (Hb F) made up of 2 alphas and 2 gammas
Beta thalassaemia
Beta thalassaemia major (missing 2 genes)
- unable to make adult Hb
- significant dyserythropoiesis
Clinical features:
Maxillary prominence
Skulls thicker
Enlarged spleen
Thalassaemias
Relative lack of globin genes
Normally 4 alpha and 2 beta globin genes
Alpha thalassaemias:
A+thal trait (missing one gene): mild microcytosis
Homozygous a+ thal trait (missing two): mild microcytosis, mild anaemia
HbH disease (missing 3): significant anaemia, abnormal shaped RBCs
Alpha thal major (missing 4): incompatible with life
Treatment:
Transfusion
Iron chelators - as iron overload major cause of mortality
HbH disease
Missing 3 alpha genes
As there is not enough alpha globin chains, causes excess beta globin chains
Beta chains join up together becoming a tetramer (HbH)
Blood transfusion required during stress
Haemaglobinopathies: Hb variants
Includes Sickle cell disease, Hb C, D, E
Sickle cell pathogenesis:
Point mutation on beta globin chain (glutamine to valine) at position 6 leads to:
- RBCs becoming rigid, and occluding blood vessels leading to tissue infarction
- RBCs have reduced life span (10d)
Clinical features:
Brain - stroke, moya moya
Lungs - pulmonary hypertesnsion
Urogenital - priapism (maintain erection)
Management:
Hydration, analgesia, prophylactic vaccinations, O2, fluids, blood transfusion
What happens when you cut yourself?
Blood vessel damage, disrupts endothelium
Exposure of tissue factor and collagen
Primary haemostasis (platelets recriuted)
Secondary haemostasis (coagulation factors activated)
Haemostasis
Primary haemostasis:
When endothelium damaged, exposes collagen and tissue factor
Platelets have receptors (GPIb) which bind to von Willebrand factor allowing platelets to adhere to vessel wall
Platelets release granular contents (ADP, thromboxane A2)
ADP allows expression of GPIIb/IIIa on platelets, which allows them to aggregrate with each other, and with fibrinogen, forms a weak platelet plug
Phospholipid is exposed on surface of platelets
Secondary haemostasis
Coagulation cascade is activated
Events:
Intiation - extrinsic pathway (due to TF)
Propagation - instrinsic pathway (due to subenothlelial collagen)
Thrombin generated, converts fibrinogen to fibrin, which is cross-linked to form stable platelet plug.
Coagulation cascade
Intrinsic pathway (PTT)
Subendothelial collagen
Factor 12, 11, 9, 8
Extrinsic pathway (PT)
Tissue factor
Factor 7
Common:
10, 5, 2 (thrombin), 1 (fibrin)
Factor 10, 5, 2 (prothrombin complex)
Factor XIIIa (13a) allows crosslinking of fibrin
Every step requires phospholipid and Ca2+
Coagulation cascade: regulation
- Tissue factor pathway inhibitor: inhibits TF and Xa
- Thrombomodulin activates protein C to APC (activated protein C)
Protein C and Protein S inactivate factor V + VIII (5, 8)
Antithrombin inactivates factor 7, 5, 2,
Coagulation cascade: fibrinolysos
As fibrin made, stimulates uPA and tPA which activates plasminogen to plasmin
Plasmin breaks down fibrin to fibrin degradation products e.g. D-dimer
a2-antiplasmin: regulates plasmin production
Plasminogen activator inhibitors: inhibits uPA and tPA
TAFI (thrombin activateable fibrinolysis inhibitor): inhibits uPA and tPA, reduces breakdown of fibrin
Lab analysis of coagulation
Assess primary haemostasis
in vivo: bleeding time
ex vivo: FBC (platelet count), platelet function (assessed by light transmission aggregometry)
Assess secondary haemostasis:
Prothrombin time (PT)
Activated partial thromboplastin time (APTT)
Thrombin clotting time (TCT)
Coagulation test
Take sample of blood, place in citrate tube (chelates Ca2+, stopping blood from clotting)
Cetrifuged creating platelet poor plasma
Ca2+ added to PPP
Clot forms
How long clot formed measured)
Prothrombin time - extrinsic pathway and common (1.0-1.2)
depends on:
- Factors VII
Factors X, V, II and fibrinogen
INR (international normalised ratio) - standardised form of PT
Activated partial thromboplastin time - intrinsic pathway
depends on:
- Factors XII, XI, IX, VIII
- Factors X, V, II and fibrinogen
Thrombin clotting time (TCT): measures conversion of fibrinogen to fibrin
Depends on:
- How much fibrinogen present
- How well fibrinogen functions
Prolonged by:
Thrombin inhibitors (heparin)
Inhibitors of fibrin polymerisation (paraproteins)
Anti-thrombotic agents
Anti-coagulants - inhibit coagulation factor
Anti-platelets - inhibits platelet aggregration
Fibrinolytic agents - Enhances lysis of fibrin clot
Anti-coagulation agents
Inhbits formtion of fibrin clot
Heparin - inhibits Xa, thrombin (IIa)
Warfain - Vit K antagonist, inhibits II, VII, VIII, X
DOACs:
Dabigatran - inhibits thrombin (IIa)
Apixaban, edoxaban - inhibits Xa
Heparin
Enhances activity of antithrombin
Anti-IIa and anti-Xa activity
Doesn’t cross placenta
Given parenterally
LMWH has superior pharmacokinetic profile, side effect profile, can be used in out-patients (as doesn’t need monitoring)
But more expensive
Not readily reverisble (UF can be reversed by protamine)
Indications:
Immediate, short acting effect
Acute DVT, PE (LMWH)
Cardiac bypass (UFH)
Warfarin
Inhibits Vit K oxide reductase, inhbitiing Vit K
Inhibits II, VII, VIII, X
Delayed onset/offset (takes 5-7 days for steady state - full anticoagulable effet)
Narrow therapeutic window
Requires INR monitoring
Indications:
AF, Acute DVT, PE, prosthetic heart valve
NOT for immediate anti-coagulation
DOACs
Dabigatran: inhibits IIa (thrombin, preventing conversion of fibrinogen to fibrin)
Apixababn, edoxaban: inhibits Xa (prevents conversion of prothrombin to thrombin)
Indications: prophylaxis venous thromboembolism
Don’t require monitoring
Contra-indications: pregnancy, breast feeding, liver disease, drugs (CYP3A4 inhibitors)
Warfarin vs DOACs
Warfarin: slow onset/offset
dosing are individualised
INR monitoring
Many food, drug interactions
Renal impairment may increase bleeding risk
Rapid reversal with Vit K
DOACs: rapid onset offset
dosing based on CrCl
annual monitoring
Few food, drug interactions
Renal impairment contra-indicated
No rapid reversing
Fibrinolytic drugs
Enhances lysis of fibrin clot
2 classes:
Kinases e.g. Urokinase
Tissue plasminogen activators: Tenecteplase
Kinases
Streptokinase, Urokinase
Binds to plasminogen - increases plasmin and directly increases breakdown on fibrin clot
- Causes fibrinolysis and fibringenolysis
Streptokinase:
- Made from streptococci bacteria
- Antigenic: can cross react with anti-streptococcal antibodies
Urokinase:
- Made from renal cells in culture so not antigenic
Indications: MI
Problems: significant bleeding risk, streptokinase antigenic
Tissue plasminogen activators
Tenecteplase, Alteplase
Activates plasminogen
Selective for clot bound plasminogen, so minimal unwanted fibrinolysis effects
Tenecteplase: short half life
Indications
- MI
- Ischaemic stroke (alteplase)
PE with haemodynamic instability (alteplase)
Side effects:
Risk of haemorrhage
Contra-indications
Haemorrhagic stroke
Major trauma
Catheter directed thrombolysis
Catheter passes through to site and fibrinolytic drugs infused
Pros:
Smaller doses
Less systemic effects
Uses:
Acute limb ischaemia
DVT
Anti-platelet drugs
Inhibits platelet activation, platelet aggregration
Clopidogrel - irreversibly blocks ADP mediated platelet aggregration
- decreases expression of GPIIb/IIIa receptors leading to reduced binding of fibrinogen
Abciximab - monoclonal antibodies which antagonise GPIIb/IIIa. Causes reduced platelet aggregration, and binding of fibrinogen
Aspirin - irreversibly binds to cyclooxygenase (blocks conversion of arachidonic acid to thromboxane A2) leading to decrease platelet activation
Phosphodiesterase inhibitor III e.g. Dipyridamole - Increased platelet conc of cAMP, decreased responsiveness to ADP leading to decrease platelet aggregration
Thromboxane synthetase inhibitors (Picotamide)
Thromboxane receptor blockers (Ifetroban)
Indications:
Cardiovascular disease
Acute MI - aspirin, clopidogrel (up to 12 months)
Cerebrovascular disease (no AF)
Acute stroke (clopidogrel)
Disseminated intravascular coagulation
Pathological activation coagulation cascade
Formation of micro-thrombi leading to ischaemia, infarction, and organ failure
Depletion of coagulation factors leading to bleeding
Causes:
- sepsis e.g. meningococcal septicaemia due to nisseria meningitidis)
- malignancy e.g. acute promyelocytic leukaemia
- severe trauma
- pre eclampsia
Symptoms: Multiple bleeding sites, petechiae, bruising of skin
Investigations
FBC+film, platelets (reduced), RBC fragmentation
Coagulation: PT (prolonged), APTT(prolonged)
D-dimer (increased)
Management:
Treat underlying case
Fresh frozen plasma+/- platelets
Heparin
Anti-thrombin concentrate
What to do if INR too high?
Stop warfarin, reduce dose
Give Vit K
Give coagulation factors (II, XII, XIII X)
How does liver disease cause coagulopathy (impaired ability to form clots)?
Poor coagulation factor synthesis (as liver produces coagulation factors)
Vit K deficient (which leads to deficient factors (2, 7, 9, 10)
Poor clearence of activated coagulation factors
DIC
Haemophilia
Haemophilia A: Factor VIII deficiency
Haemophilia B: Factor VIIII deficiency
X-linked
Prolonged APTT (as factor 8 and 9 due to intrinsic pathway)
PT normal (extrinsic pathway)
Treatments:
Education
Desmopressin
Replacement therapy - FFP
Von Willebrand disease
AD
Most common anti-coagulation disorder
Reduced vWF
+/- reduced platelet aggregration
reduced VIII (as vWF binds to VIII and prolongs its half life)
Mucosal type bleeding pattern
Clinical features: epistaxis (nose bleed), mennorhagia, GI bleeding, haemoptyis
Severe inherited platelet disorder
AR
Mucosal type bleeding pattern
Bernard Soulier Syndrome (defective GPIb/V/IX)
- platelet adhesion impaired, macrothrombocytopenia (englarged platelets) on blood smear (as produces immature platelets)
Glansmanns thrombasthenia (defective GPIIIa/IIb) - platelet aggregation impaired
Management:
Pressure
Desmopressin
Platelet transfusion
Thrombophilia: Inherited
Deficiencies of natural anticoagluants:
- Anti-thrombin
- Protein C
- Protein S
Specific genetic mutations:
Factor V leiden: mutation in V, stopping activated protein C to cleave factor 5, leading to increase in blood clotting
Prothrombin gene mutation - increase prothrombin and thrombus formation
Lupus anticoagulant
Antibody that binds to phospholipids, leading higher chance of blood clotting
Anti-phospholipid syndrome: persisting Lupus anticoagulant + thrombosis
Investigations
APTT prolonged
APTT 50:50 mixing partially corrects
DRVVT ratio prolonged
Prolonged APTT
Perform 50:50 mix - combine 1 part normal plasma and 1 part patient’s sample
If APTT fully corrects: prolongation due to factor deficiency (as normal plasma replaced the factors)
If APTT partially corrects: inhibitor(e.g. lupus anticoagulant)
Thrombophilia - acquired
Hyercoagulable state due to another condition
E.g. Antiphospholipid syndrome - presence of antiphospholipid antibodies e.g. Lupus anticoagulant, anti cardiolipin antibodies
Disrupts Annexin 5 shield, exposes excess phospholipid
Clinical scenario:
- Venous/arterial thrombosis
- Recurrent miscarriage
Idiopathic thrombocytopenic purpura
Self limiting postviral illness where immune system destroys platelets
Most common in children
Presents with purpuric , epistaxis, mennorhagia, (spleen not enlarged)
Treatment
Steroids, IVIG
Infectious mononucleosis
EBV infection resulting in lymphocytic leukocytosis (increase lymphocytes as fighting infection) - comprising of CD8 T cells
Clinical features: fever, tonsilitis, cervical lymphadenopathy. splenomegaly
Tests: monospot test - detects heterophile antibodies (produced during EBV reaction which reacts with animal (sheep, horse) antibodies causing blood to agglutinate)
EBV titres
Treatment
Self limiting
Amoxicillin should not be given as due to virus not bacteria, and can cause amoxicillin rash
Complications:
Can become dormant in B cells
A 21 year old medical student presents with a facial rash (butterfly distribution) and polyarthritis.
- What is likely diagnosis?
Her coagulation screen shows
PTT: Prolonged (did not correct with 20% normal plasma)
PT: Normal
Fibrinogen: Normal
Platelets: Normal
Likely cause?
SLE
Prolonged anti-coagulant due to lupus anticoagulant
Pt has increased thrombotic tendency (different to what laboratory tests shows)
Haemolytic uraemic syndrome
Due to E.coli 0517
Symptoms: bloody diarrohea
Clinical features: anaemic, thromocytopenic, uraemia
RBCs look fragmented
Coagulation not affected
Hodgkin’s lymphoma
Malignancy from mature B cells. Characterised by presence Reed Sternberg cell (large, lots of cytoplasm, bilobed nucleus. Owl’s eye appearence)
Staging:
History for B symptoms (systmeic symptoms - weight loss, night sweats, pyrexia), lymphadenopathy
- physical examination
- CT
- BM to determine stages 1-4 (1=localised, 2= 2 or more sites on same side of diaphragm, 3=both sides of diaphragm, 4=widespread)
A 71 year old female patient is found to have painless cervical lymphadenopathy. She is otherwise well. She has rubbery nodes (1-2cm) in all areas and splenomegaly of 2 fingerbreadths.
Full blood Count
White count 100 x 109/l (NR 4-10)
Haemoglobin 13 g/l (NR 12-17)
Platelets 200 x 109/l (NR 150-400)
The WBC differential shows 90 x 109/l lymphocytes. These are later shown to be B cells.
Chronic lymphoid leukaemia (CLL)
Monoclonal B cells
Different from chronic myeloid leukaemia (CML), as doesn’t change to acute leukaemia (whereas CML can become AML or ALL)
Major haemorrhage
Definition: Loss of more than one blood volume (>5L in 70kg adult) within 24 hours
Loss of 50% total blood volume in 3 hours
Bleeding excess of 150mL/min
Management:
A, B, C
O2
IV access
Bloods - FBC, coagulation factors, fibrinogen
Tranexamic acid
Bloods - O neg, use group specific where possible
Complications
Hypothermia, acidosis, coagulopathy
AML
Proliferation of myeloid blast cells in BM (which can’t differentiate into RBCs, neutrophils, platelets leading to BM failure)
Most common leukaemia in adults
Death within days/weeks if untreated
Aetiology
Unknown, chemo, genetic e.g. Faconi’s syndrome, blood disoders e.g. MPS, MDS
Clinical features:
Rapid onset symptoms, fatigue, infection, bleeding, bone pain, hepatosplenomegaly
Diagnosis:
FBC: Anaemia, thrombocytopenia, neutropenia, increased WBCs
Blood smear: blast cells, granualated with Auer Rods
Bonr marrow biopsy (definitive diagnosis): >20% blast cells (large, little cytoplasm with punched out nucleus)
t(15:17) - acute promyelocytic leukaemia (can also cause DIC)
Management
High dose chemo +/- SCT (<60)
Low dose chemo (>60)
Supportive treatment (elderly)
Chemo - Anthracycline, cytarabine
ALL
Malignant clonal disorder characterised by increase in lymphoid blast cells (mostly B cells)
80% childhood leukaemias
Clinical features:
lymphadenopathy (enlarged lymph nodes), pupuric rash, bone pain, CNS symptoms (can cause meningeal leukaemia), testicular infiltration
Investigations
FBC: Anaemia, neutropenia, thrombocytopenia, leukocytosis (increased WBCs)
Bone marrow trephine biopsy: >20% lymphoblasts in BM
High nuclear:cytoplasm ratio
Cytogenetics:
hyperploidy (excess chromosomes) good prognosis
t(4:11), t(9:22) poor prognosis
CSF: cell count high, glucose low, blast cells - meningeal leukaemia
Managment:
Chemo
Supportive treatment: blood transfusion, FFP, antibiotics (increase risk of infections) - for older pts
Those with poor prognosis, relapsed considered for BMT
Silbings have 1/4 chance of being HLA matched
Chronic myeloid leukaemia
Increase in mature myeloid cells (neutrophils, basophils, eosinophils)
More in middle-aged
Causes: radiation
Clinical features:
asymptomatic, lethargy, night sweats, weight loss, splenomegaly
Investigations
FBC: Increased WBCs, anaemia, increased/decreased platelets
Blood smear: mature myeloid cells
basophil count >20% would diagnose them in blast phase
BM biopsy: Granulocytic hyperplasia
Cytogenetics, PCR: BCR-ABL (required for diagnosis)
Stages:
Chronic - accelerated - blast crisis (AML/ALL)
Pathogenesis
Philidelphia chromosome - translocation between ch. 9 and 22 t(9:22) leading to fusion of BCR-ABL gene, creating abnormal tyrosine kinase
Treatments:
Imatinib (Tyrosine kinase inhibitor)
Chronic Lymphoid Leukaemia (CLL)
Commonest leukaemia
Incidence rises with age
Proliferation of neoplastic mature, lymphoid cells ( naive B cells)
Cells co-express CD5 (normally expressed on T cells) and CD20
Clinical features: aymptomatic, lethargy, night sweats, weight loss, lymphadenoapthy, anaemia, SOB
Insiduous
Complications
Autoimmune haemolytic anaemia - (as when try to make immunoglobulins, do a crap job)
Neutropenia
Pulmonary infections (strep. pneumoniae, pneuomocystis jirovecii) - as B cells don’t mature into plasma cells so increased infection
Diagnosis:
Most are incidental
FBC - increased WBC with lymphocytosis (increased no. lymphocytes), anaemia
Blood smear: smudge cells (looks like cell has been smash)
Clinical Staging: BINET
Stage A: < 3 involved lymphoid tissue (nodes, spleen, liver)
Stage B: > 3 involved lymphoid tissue
Stage C: Anaemia, thrombocytopenia
17p deletions
Aggressive disease
del 17p causes loss of p53
Lymphoma
Neoplastic disorders which causes clonal expansion of lymhoid cells involving lymoh nodes, and lymhoid tissue e.g. MALT, spleen
Divided into Hodgkin’s lymphoma (25%) and Non-Hodgkin’s lymphoma (75%)
Clinical features:
Lymphadenopathy (painless, rubbery), B symptoms, splenomegaly, anaemia
Investigations
History: B symptoms
Clinical examination: lymph nodes
Blood tests - FBC, U&Es, ESR
Imaging - CT
BM - aspirate (sucking out marrow), trephine (BM core)
Staging (Ann Arbor classification)
Stage 1: 1 lymph node group
Stage 2: more than 1 LN group but same side diaphragm
Stage 3: more than 1 LN group different side diaphragm
Stage 4: extranodal involvement e.g. liver, spleen
A and B - indicates absence (A), presence (B) of B symptoms
Non-Hodgkin’s lymphoma
Group of malignant disorders involving lymphoid cells
More common than HL
Split into B and T cell
Each split into Indolent and Agressive
Low grade (indolent) lymphoma - low rate prolfieration/apoptosis. Uncurable
High grade (aggressive) lymphoma - neoplastic cells large, prominent nucleoli, high rate cell divison/death. Often curable.
B cell indolent: follicular lymphoma
B cell aggressive: diffuse large B-cell lymphoma, Burkitt’s lymphoma
Clinical features: Painless lymphadenopathy, B symptoms, cytopenias (due to marrow failure), abdominal disease
Follicular lymphoma
Indolent (low grade) B cell lympoma
Neoplasm of B cells that makes follicle like nodiles
Characterised by translocation t(14:18) leading to upregulation of BCL2 (anti-apoptotic protein)
Slow growth but reduced apoptosis
Incidence increases with age
Clinical presentation: Late adulthood, painless lymphadenopathy
Complications: Can progress to diffuse large B-cell lymphoma
Treatment:
Aimed at symptom control
Early stage - radiotherapy
Advanced stages:
Rituximab
Diffuse large B-cell lymphoma
Hetergenous group of B cell lymphomas
High grade B cell lymphoma
Resembles activated B-cells
Commonest subtype of Non-Hodgkin’s lymphoma
Clinical features:
Aggressive
Lymphadenopathy - rapidly enlarging LN mass
Extra-nodal presentation: Waldeyer’s ring, GI, skin
B symptoms
Treatment:
R-CHOP (rituximab, cyclophosphamide, adriamycin, vincristine, prednisolone)
Burkitt’s lymphoma
High grade B cell lymphoma (highly aggressive)
Neoplasm of B cells in germinal centre
- Mostly in children
Characterised by translocations involving MYC gene t(8:14) leading to high rate of proliferation, apoptosis
- can cause tumor lysis sydrome (cancer cells release intracellular contents when destroyed leading to arrthymias, sudden death)
Clinical features:
short history, marked B symptoms, rapidly growing tumor
Extranodal disease:
- Jaws (African form), facial bone
- Ileocoecal region of GI tract (sporadic form)
- CNS involvement
Histology:
- starry sky appearence
Treatment: CODOX-M / IVAC
CODOX-M: (cyclophosphamide, (O) vincistine, doxorubicin, methotrexate)
Hodgkin’s lymphoma
Haematological malignancy from mature B cells. Characterised by Reed-Sternberg cells (bi-lobed, prominent nucleolus, gives owl’s eye appearence)
Strong expression of CD30
Assoc. with EBV infections
Incidence peaks at 20-30, then 50
Clincal features: painless lymphadenopathy (cervical common), cough, SOB, itch can precede diagnosis, alcohol related pain
Subtypes:
Classical Hodgkin’s lymphoma (90%) and nodular lymphocyte predominant
Classical Hodgkin’s lymphoma split into:
Nodular sclerosing (most common) - collagen bands divide LN into nodules. Uusally young, female, has cervical lymphadonapthy
Lymphocyte rich - large no. of lymphocytes
Mixed cellularity - fewever lymphocytes, more RS cells. Lots of eosinophils
Lymphocyte depleted - few lymphocytes, lots of RS cell. Worst prognosis
Spreads from one nodal group to adjacent group. Later, haemotological spread to liver, lungs
CXR: can show widening of mediastinum, pleual effusion
Complications: risk of Br. Ca in females, cardiovascular disease, infertility
Treatment
ABVD (adriamycin, bleomycin, vinblastine, dacarbazine)
1 and 15 of 28 day cycle
Plasma cell myeloma/mutiple myeloma
Neoplasm of mature plasma cells
Abnormal plasma cells produce paraprotein (monoclonal protein) or only light chain of immunoglobulin produced (light chain myeloma)
IgG most common
Neoplastic cells resemble plasma cells
- Mostly in elderly
Clinical presentation: CRAB
hyperCalaemia, renal insufficiency (as light chains deposit in renal tubules), Anaemia, Bone lytic lesions (as plasma cells leads to OC activation)
Classical triad: increased plasma cells in BM, paraprotein, lytic bone lesions
Investigations:
Blood tests: FBC (rouleaux), ESR, serum electrophoresis (spike in M band (monoclonal protein: IgG or IgA)
Urine tests - light chains (Bence Jones protein (light chains))
BM aspirate (increase no. of plasma cell)
Imaging: MRI (bone lytic lesions, pepper pot skull)
Complications: SC compression
Diagnosis:
>10% plasma cells in BM + at least one of CRAB symptoms
Treatment:
Asymptomatic (smoudlering) - observe
Symptomatic: Chemo inc. steroids + thalidomide
Radiotherapy
Supportive treatment: bisphosphonates
Monoclonal gammaopathy of undetermined significance
(MGUS)
<10% plasma cells in BM
Serum M protein <30
Bence Jones protein rare
No symptoms characteristic of plasma cell myeloma (anaemia, hypercalcaemia, renal dysfunction, lytic bone lesions)
Can progress to myeloma
Thrombocytopenia
Clinical features: pupura, mucosal bleeding
Causes:
BM failure
ITP (idiopathic thrombocytopenia purpura)
hypersplenism (overactive spleen)
Henoch Schonlein purpura (normal platelets)
What is haematinic (increases RBC production)?
A.Selenium
B.Vitamin B6
C.Folic acid
D. Vitamin B12
Folic Acid
Hypospenlism doesn’t cause increased risk of what infection?
E.coli
Increases risk of Strep. pneumoniae, haemophilus influenzae, nisseria meningitidis
Definition leukaemia vs lymphoma
Leukaemia: malingnancy of leucocytes in BM or blood
Lymphoma: malignancy of leucocytes in LN or lymphoid tissue e.g. MALT. Usually presents as a tumor mass
Plasmacytoma
Single localized tumor of monoclonal plasma cells
Microcytic and hypochromic anaemia
SALTI
Sideroblastic anaemia
Anaemic of chronic dissease
Lead poisoning
Thalassaemia
Iron deficiency anaemia
ITP (idiopathic thrombocytopenia purpura)
Autoimmune disease against platelet antigens (GPIIb/IIIa) which are consumed by splenic macrophages
Most common cause of thrombocytopenia
Acute form in children, weeks afer viral infection, self-limiting
Clinical features: peteichae, epistaxsis, menorrhagia
Complications: intra-cranial bleeding
No splenomegaly
Labs:
Decreased platelet count
PT, aPTT normal
megakaryocytes on biopsy
Treamtent:
Steroids, splenectomy
