Haematology Flashcards
Causes for anaemia with low retics
Marrow Problem:
Iron, B12, folate, PRCA, AA, anaemia of chronic disease
Causes for anaemia with high retics
Hemolysis
Thal
Blood loss
Microcytic anaemia causes
Thal Anaemia of chronic dis Iron def Lead poisoning Siderblastic anaemia
Normocytic anaemia causes
Renal failure Blood loss Haemolytic anaemia Anaemia of chronic dis Bone marrow failure - AA, infiltration, chemo, PRCA
Macrocytic anaemia causes
Megaloblastic - B12, folate, cytotoxic drugs ETOH Myelodysplasia Hypothyroidism CLD
Target cells
Iron def
Liver disease
Haemoglobinopathies
Post splenectomy
Stomatocyte
Liver disease, ETOH
Pencil cell
Iron deficiency
Spherocyte
Warm Hemolysis, septicemia, hereditary spherocytosis
RBC Fragments
DIC, HUS, microangiopathy, TTP
Elliptocyte
Hereditary elliptocytosis
Tear drop/ poikilocytes
myelofibrosis, extramedullary haemopoesis
Ferritin role in iron regulation
Iron which is not required is stored by ferritin
Water soluable
Hepcidin Role in iron regulation
Expression mostly in the liver
Regulates iron absorption and the distrubution of iron to tissues
-Binds to ferroportin in the enterocyte or reitculocyte and breaks down ferroportin so irons remains within the cell and does not go into blood stream
Regulators of Hepcidin expression
Increase Hepcidin:
- Inflammation
- Excess iron
Low levels Hepcidin
- Iron def
- Hypoxia (EPO)
- Erythropoesis
- Haemalytic anaemia, Thal, Haemachromatosis (inappropriately low)
Role for Soluble transferrin receptor in iron deficiency
In absence of erythroid hyperplasia, Iron def is prinicipal cause of raised soluble transferrin receptor
NOT elevated in anaemia of chronic disease
Helpful in differentiating iron def and inflammation from anaemia of chronic disease
What is the role for globin chains in Hb structure
Protect haeme from oxidation, so that they are efficient in transporting O2
Adult Hb
HbA - alpha2Beta2
HbA2- alpha2delta2
HbF
Alpha2gamma2
HbS pathology
Sickle Cell anaemia
-Valine for glutamic acid in 6th position of beta chain
Sickle cell anaemia vs disease
SCA - homozygous for HbS
SCD - Coinheritance of Beta thal gene
HbE cause
G to A in codon 26 of beta globin gene
- Structurally abnormal
- Behaves like Beta thal mutation
Complications and Mx of Transfusion dependent Beta thal major
Cx:
-Iron overload, OP, endocrinopathies, renal impairment
Mx
-Transfusion to avoid bony deformity, Iron chelation, consider splenectomy, Mx complications from iron overload
Precipitants of Sickle cell crisis
Hypoxia Hypo/hyperthermia Altitude Acidemia Pregnancy Sepsis
Ix that suggest intravascular haemolysis
Raised plasma haemoglobin
Haemoglobinuria
Urinary haemosiderin
Methaemalbuminaemia
Hereditary Spheroctosis
Autosomal Dominant
MCHC increase >360g/L
Defect in cytoskeleton of RBC membrane
Features:
-Jaundice, splenomegaly, gall stones, leg ulcers, haemolytic crisis, aplastic crisis
Dx:
-Blood film, negative DAT, flow cytometry, reduced binding of eosin-5 maleimide
Mx: Splenectomy +/- folate
Dx and Mx of warm AIHA
Extravascular hemolysis
Antibody reacts with RBC at 37 degrees (IgG mediated)
Causes classically:
-SLE, CLL/lymphoma, Drugs
Dx: Hemolysis screen positive, Spherocytes, Positive DAT
Mx:
- Supportive and transfusion
- Steroids
- IVIG
- Folate (increased RBC turnover)
- Aza/Mercaptopurine
- Consider DVT prophylaxis
Second line:
-Rituximab, +/- Splenectomy, IVIG
Associations of cold agglutinins
Mycoplasma pneumoniae
EBV
Lymphoma
Cold agglutinins haemolysis Dx and Mx
DAT +ve to C3d only not IgG
Features of intravasular haemolysis
-Mx:
Keep warm
Rituximab
Steroids only helpful if it is mixed cold and warm haemolysis
MAHA definition and causes
Hamolytic anaemia and thrombocytopenia
Causes:
- TTP
- HUS/aHUS
- Pregnancy
- DIC - Prosthetic valves
- Drugs: Gemcitabine
- Cancer
- SLE
Diagnosis and Mx of TTP
Low ADAMTS 13 <10%
Tx
- Apheresis, FFP, steroids, Rituximab
- Caplacizumab (anti vWF - not available yet)
PNH Features
Pancytopenia
VTE
Chronic paraoxysmal intravascular haemolysis, dark urine
Defective protein PIG-A whish is essential for formation of the GPI anchor; a structure that attaches several srface proteins to the cell membrane: CD55/CD59 (protects RBC from complement mediated lysis)
Cells sensitive to complement mediated lysis
Gold Standard Ix:
-Flow cytomettry lack of CD55/CD59
PNH Mx
Eculizumab
Anticoagulation lifelong after 1st thrombosis
Transfusions +/- iron infusions
Universal plasma donor
AB blood type
Have no antibodies in serum
Massive transfusion protocol
Start with/ RBC:FFP:Plt close to 1:1:1 ratio
(4 units blood and FFP, and one pool platelets)
-Next pack add in Cryo 8-10 units
After increased ratio of plasma to RBCs improves mortality
TACO Definition and Mx
Transfusion Associated Circulatory Overload
- Within 2 hours and rapid
- Usually after large volume
- HTN common
CXR: pulmonary oedema
Mx: O2, Frusemide, ventilatory support
TRALI definition and Mx
Transfusion Related Acute Lung Injury
- Within 6 hours, progresses to ARDS
- Initiated by small volume
- Moderate hypotension
Mx: O2 and ventilatory support
Acquired Thrombophilias
APLS
Cancer - LMWH better than warfarin
Hereditary Thrombophilias
F5 Leiden/APC resistance
Prothrombin gene mutation
Antithrombin deficiency
Protein C and Protein S deficiency
VTE Duration of anticoagulation
Provoked (except cancer)
-3-6 months
Unprovoked
- Minimum 6 months
- Decision to stop based on:
- -# of previous events; >1 cont.
- -Male»_space;>female recurrence
- -High risk thrombophilia
- -Mobility
- -Elevated D-dimer at completion of initial Rx phase
- -Obesity
- -Sequelae of clot: PulmHTN, PPS
CAPS Defintion and Mx
Characterised by widespread thrombotic disease with multiorgan failure
-Mortality ~50% despite anticoagulation and immunosuppression
Mx:
-Steroids, immunosuppression, PLEX, aggressive anticoagulation
APLS Diagnostic Criteria
1 clinical and 1 lab criteria needed
Clinical:
- Vascular thrombosis
- 3x miscarriages
- 1x stillbirth
- 1x premature birth due to placental insufficiency or eclampsia
Lab:
-B2GP, LAC, or Anticardiolipin positive in high titres on 2 or more tests 12 weeks a part
Lupus anticoagulant testing
- Suspect when prolonged APTT
- Fails to correct with mixing
- Normal TCT
- Prolonged reptilase time
Corrected APTT testing
First mix plasma with normal plasma. If it corrects, then factor deficiency will correct, but an inhibitor will not correct.
Correction is defined as coming back within 4-5 seconds of controlled plasma’s APTT
Which APLS Ab is the most thrombotic
Lupus anticoagulant
Also the more Abs positive the higher the risk of thrombosis
APLS and Pregnancy:
APLS Abs and previous thrombosis, but no pregnancy complication
Cont with therapeutic anticoagulation
APLS and Pregnancy:
APLS Abs and no prior thrombosis or pregnancy complication
Monitor in antepartum period
Post partum prophylaxis for 6 weeks
APLS and Pregnancy:
APLS Abs and >1 fetal loss after 10 weeks
low dose aspirin and prophylactic LMWH during pregnancy
+Post partum prophylaxis for 6 weeks
APLS and Pregnancy:
APLS Abs and Hx of preeclampsia
Low dose aspirin in 2nd and 3rd trimester
Post partum prophylaxis
VTE prophylaxis in pregnancy if not APLS
prophylactic LMWH if prev unprovoked VTE or whilst on COCP
MOA of heparins/LMWH/Fondaparinux
Inhibit coagulation through antithrombin
-Directly inhibit factors II, X (and IX , XI)
Fondaparinux: pentasaccharide used in HITS with normal renal function
MOA DOACs
Rivaroxaban and apixaban block factor Xa
Dabigatran blocks thrombin activity
Dabigatran level test
Dilute Thrombin Clotting Time (TCT)
Trade name: Haemoclot
How long to W/H DOACs prior to OTs
Low risk: 24 hours pre op
High risk: 2-3 days prior
Dabigatran reversal methods
Idarucizumab
HDx
Activated charcoal if just recently ingested
Apixaban and Rivaroxiban reversal
Limited evidence
Some case reports suggest prothrombinex
Andexanet Alfa (Decoy Xa level for these agents to bind to) - not PBS approved
DAT testing
Detects antibodies attached to RBCs
Red blood cell modifications:
ALL PRBCs are leucodepleted
Irradiated
-For prevention of Transfusion related GVHD as there are still very few leucs in PRBC
Washed
-IF previous allergic rxn to plasma
CMV seronegative
-For Tx and Pregnant patients
Platelets
Single donor or pooled from multiple
Lasts 5 days at room temp (most likely to cause sepsis due to this)
Indication:
- Bleeding in setting of severe thrombocytopenia
- No effective in patients with rapid platelet destruction (e.g. ITP, TTP)
FFP
Plasma with coagulation factors (V, VII, VIII)
Potential to cause infusion rxn or allergic rxn as contains all plasla proteins, antigens, viruses that were in blood at time of collection
Cryoprecipitate
From FFP precipitate when thawed
Rich in fibrinogen, FVIII, XIII, vWF, and fibonectin
Indication:
-Only fibrinogen replacement like in DIC
Prothrombinex
Coagulation factor concentrate (II, IX, X and low level of VII)
Also contains antithrombin and heparin
Indication:
warfarin reversal
Immediate Haemolytic transfusion rxn
Usually due to ABO incompatibility
Results in massive intravasular hemolysis and possibly DIC
Mx
- Stop transfusion
- IV saline/resus
- Correct DIC
- Aim UO >100 ml/hr
- Recheck blood group and Xmatch
- hemolysis screen
- Culture unit for bacteria (clostridium welchii)
Delayed haemolytic Transfusion Reaction
Extravascular hemolysis
Antibody coated RBCs are cleared by reticular system
Usually prevented by Xmatch
Occurs 1-2 weeks post transfusion
Supportive Mx, Ix with hemolysis screen
Febrile non hemolytic transfusion reaction
Definition:
-Increase temp >1 degree C
Cause:
- Patient’s Antibodies against donor leukocytes and cytokine storm (most likely cause)
Prevention:
-Leucodepletion (which is done to all RBCs now)
Mx
-Stop transfusion and supportive Mx and exclude other causes
Transfusion associated GVHD
Transfusion of viable T cells that then proliferate and attack the recipient
Onset: 8-10 days
>90% fatal
Presentation:
Fever, rash, N+V+D, hepatitis, pancytopenia
Ix: Tissue typing and Bx
Prevention: Irradiation of RBCs
Allergic Rxn with transfusion
Most commonly due to IgA
-Screen for IgA deficiency/antibodies
Post transfusion Purpura
Profound thrombocytopenia <10, wet purpura (mucosa), platelet refractoriness
Which virus has the highest risk of transmission with transfusion
Hep B
1/800,000
Factors produced by normal endothelium to prevent platelet adhesion
NO
Prostacyclin
Aspirin MOA
prevents platlet aggregation by COX inhibition which prevents formation of thromboxane A2 which promotes platelet aggregation
Clopidigrel and Ticagrelor and prasugrel MOA and which is reversible
Blocks ADP from binding to P2Y12 receptor on platelets
Role of P2Y12 receptor activation is to promote binding of GPIIb/IIIa receptor to fibrinogen to form clot
Ticagrelor is the only reversible one.
Tirofiban MOA
GPIIb/IIIa receptor blocker
Dipyridamole MOA
Phosphodiaesterase inhibitor which prevents cAMP to be changed to AMP.
Increased cAMP decreases Calcium release from platelet which prevents aggregation of platelets
APTT is a measure of which pathway?
Intrinsic pathway
Above factor 10
Measures the clotting time of the plasma (without tissue factor I.E extrinsic pathway)
PT is a measure of what pathway?
Extrinsic pathway
Factor 7 essentially
APTT and PT together assess a problem in what part of the coagulation cascase
The final common pathway (Factor 10 and down)
What does INR measure
Measures the clotting time of plasma in the presence of optimal concentration of tissue factor AKA thromboplastin.
Indicates overall efficiency of the extrinsic clotting system
Causes for prolonged APTT that correct with mixing
Factor deficiency
Derranged LFTs
Vit K deficiency
Causes for prolonged APTT that DO NOT correct with mixing
Lupus anticoagulant
Factor specific inhibitors
Heparin
Abnormal Fibrinogen
Causes of prolonged Thrombin Clotting Time when performed after prolonged APTT doesnt correct with mixing
TCT reflects the action of thrombin on fibrinogen
Abnormal fibrinogen
Heparin
Paraprotein esp IgM
Reptilase Time
Uses reptiliase instead of thrombin
Unaffected by heparin
Remains prolonged with abnormal fibrinogen
Haemophilia A
Factor 8 Deficiency
X linked recessive
Haemophillia B
Christmas disease
Factor 9 deficiency
X linked recessive
Differentiating platelet defects from clotting factor deficiency
Platelets defect:
- Skin, mucus membranes, GI
- Bleeding after minor cuts
- Petechiae
- Immediate bleeding after surgery
Clotting Factor Def:
- Deep in soft tissues, muscles, and joints
- Large ecchymoses
- Delayed and severe bleeding after surgery
Haemophilia A Mx
- Biostate
- Factor 8 and vWF - plasma derived - Recombinant Factor 8
Haemophilia B Mx
Factor 9 replacement either plasma derived (MonoFIX) or recombinant (BeneFIX)
DDAVP for haemophilia patients and SE
Can be used in mild cases
Stimulates transient 3-4x increase in Factor 8 and vWF levels as released from storage sites
SE:
Hyponatremia
Fluid retention
Tachyphylaxis