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Y3 Lecture week III > Hemorrhagic disorders > Flashcards

Hemorrhagic disorders Flashcards

1
Q

Coagulation pathway

A
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2
Q

What helps to balance coagulation out?

A

Antithrombin, Protein C, Protein S -> to balance coagulation out and break clots down (this is as body is at the state of constantly making clots) -> if any of these ‚balancing’ molecules will be impaired = thrombotic problem

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3
Q

What’s Von Willebrand factor? What’s its role?

A

VWF -> large adhesive glycoprotein that is required from platelet adhesion to endothelium at site of vessel injury, platelet aggregation (to form platelet plug) and stabilisation of factor VIII in a circulation (factor VIIIa is required for factor X activation)

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4
Q

What questions to ask in the Hx in order to identify the possibility of a pt having a bleeding disorder?

A
  • Questions about iron deficiency and blood transfusions -> to what extend they bleed (what treatment was required)
  • Ask about tonsillectomy -> if pt had a procedure and did not bleed -> high chance that no bleeding disorder
  • Dental extraction -> did they need to stitch it/ go back to dentist (due to heavy bleeding)
  • Did they start having bleeding problem after starting anti-coagulant (that may be the cause)
  • if bruises come out possibly in the places where we do not expect to hit ourselves/bump onto things
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5
Q

What’s the normal number of platelets? ( range)

A

Normal number of platelets 150 - 450 (this is considered as more than we need)

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6
Q

At what point (level) do we treat low number of platelets?

A

We treat platelets that are about 30 or less

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7
Q

Ix in suspected bleeding disorder (and justification)

A
  • Renal function -> uraemia can interfere with platelet function
  • Liver function -> coagulation proteins
  • Haematinics: folate and B12 -> we need it to make platelets
  • Paraprotein -> is there an abnormal protein?
  • PT (extrinsic pathway/factor VII)
  • APTT (intrinsic pathway; factor XII)
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8
Q

What does PT look at?

A

Prothrombin Time (PT)

​

  • PT looks at extrinsic pathway (factor VII etc)
  • long prothrombin time -> long for the blood to clot
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9
Q

What does APTT look at?

A

APTT looks at intrinsic pathway (factor XII, kallakerin etc)

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10
Q

Causes of long PT

A
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11
Q

causes of long APTT

A
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12
Q

What findings may be suggestive of coagulation problems? (2)

A

•Factor inhibitors = autoantibodies against coagulation factors

•Lupus anticoagulant = autoantibodies directed against phospholipid -> can cause artificially prolonged APTT (due to consumption of phospholipids that are put into the tube - so blood
cannot clot properly -> it is a false positive result)

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13
Q

What ‘other’ Ix we perform in a pt with suspected coagulopathy?

A
  • Bleeding time - we lancet somebody arm and see how long it takes to bleed
  • Mixing studies- patient’s plasma and somebody else’ plasma mixed together; if there is a deficiency of coagulation factor -> patient sample will get better (as normal stuff are put with it); if anti-body against factors causes the problem - it will not get better as it will destroy somebody else’s factors
  • D-dimer - breakdown product of fibrin
  • Factor assays - we can see how the factors behave in terms of their activity levels
  • Genetics -> to directly look for mutations

• Global coagulations assays -> used in trauma and surgical setting; how long does it take for

the blood to clot

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14
Q

What factors deficiencies are there in:

Haemophilia A

Haemophilia B

A
  • Haemophilia A -> factor VIII deficient
  • Haemophilia B -> factor XI deficient
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15
Q

What is (a simple) genetic mechanism of hemophilia?

A

X linked

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16
Q

What abnormality is seen on Ix of Haemophilia?

A

As factors VIII and IX belong to intrinsic cascade -> prolonged APTT (as intrinsic cascade is affected)

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17
Q

Complications/consequences of haemophilia

A
  • Haemarthrosis - bleeding into joint spaces
  • Haemophilic Arthropathy -> result of haemarthrosis
  • Intramuscular bleeds
  • Intracranial bleeds
  • Haematuria
  • ‘hidden bleeds’
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18
Q

Pathology of Haemophilic Arthropathy

A

recurrent bleed into joint space -> inflammation is activated -> destruction of the joint -> changes in the joint -> functional problems

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19
Q

Treatment of haemophilia

A

To replace what’s missing - clotting factors:

  • So for patient with haemophilia A -> we give factor VIII -> to bring missing factors levels up to normal
  • DDAVP -> desmopressin injection -> to release endogenous stores of factor VIII and vWF (as vWF will be released so more factor VIII too as it is bound to vWF) -> for people with mild disorders we can push up the factor levels to normal) *only effective for Haemophilia A treatment
  • Tranexamic acid -> stops bbreakdown of clots (anti- thrombolytic)
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20
Q

Possible complications of Haemophilia treatment

A

•Person with severe haemophilia is not used to high levels of missing factors -> so if they are administrated -> antibody against them can be developed*

*more common in haemophilia A

  • immune modulation -> someone is given immuno-active protein
  • Thrombosis -> perhaps over-treated -> too much coagulation -> clot
  • anaphylaxis
  • infections (e.g. Hep B, HIV, Hep C, etc - before the screening was introduced)
21
Q

Genetics behind Von Willebrand Disease

A
  • Type 1 and 2 vWD are autosomal dominant

*sometimes type 2 may be recessive

  • Type 3 autosomal recessive
22
Q

Pathophysiology of Von Willebrand Disease

A
  • Deficiency in quality or quantity of vWF
  • Deficiency of vWF will show primarily in organs with extensive small vessels (e.g. skin, GI, uterus)
23
Q

What type of Von Willebrand Disease is most common + features

A

Type 1 is most common

  • mild bleeding symptoms (e.g. nosebleeds)
  • occasional more severe symptoms

*blood type may affect the presentation of vWD and severity of its symptoms

24
Q

What severity of symptoms type 2 vWD has?

A

Type 2: second most common type

  • mild to moderate symptoms
25
Q

Clinical presentation/ features of Von Willebrand Disease

A

Clinical features: bleeding tendency, easy bruising, nosebleeds, bleeding gums (specific to women: heavy menstrual periods and blood loss during child birth)

*depend on severity and type of vWD

26
Q

Diagnosis (Ix) of Von Willebrand Disease

A
  • blood plasma of patient is investigated for qualitative and quantitative deficiencies of vWF
  • factor VIII levels -> as factor VIII is bound to vWF (deficiency of vWF can lead therefore to

reduction in factor VIII) -> elevation of PTT (takes longer to clot as factor is reduced)

  • coagulation studies (not routinely performed, for type 2) -> to look at platelet interaction with sub endothelium
  • other specialised tests

Detection of vWD is complicated as vWF is an acute phase reactant -> levels may be raised in infection, pregnancy and stress

Other tests: FBC, APTT with INR, thrombin time (TT) and fibrinogen level; test for factor IX if haemophilia B is suspected

27
Q

Desmopressin in management of Von Willebrand Disease

  • use
  • MoA
  • routes of administration
  • contraindications
A

Desmopressin (analogue of vasopressin; natural anti-diuretic) -> use in cases of minor trauma, preparation for dental or minor surgical procedures

MoA: Desmopressin -> release of vWF stimulated from endothelial cells -> level of vWF and VIII is increased

Available as: intra-nasal preparation or IV

Contraindication: type 2b of vWD (risk of thrombotic complication and increased thrombocytopenia)

28
Q

Management of Von Willebrand Factor

A
  • Desmopressin
  • Oestrogen - containing medication - for women with heavy menstrual bleeding
  • Human - derived medium - purity factor VIII (containing vWF)-> for patient undergoing scheduled surgery or having clinically significant haemorrhage
  • Contraceptive pill -> if someone has problem with menorrhagia
  • Plans before the surgery
  • combination of vWF and factor VIII -> to replace what’s missing
29
Q

Two types of platelets disorders. What do they mean?

A

A. Quantitative - a body is not producing enough platelets, or destruction is increased (e.g. destroyed in the spleen, hereditary disorders) etc.

B. Qualitative - proteins being missed, platelet proteins abnormalities, drugs reducing/inhibiting platelets’ activity, systemic disorders, haematological disorders etc

30
Q

Causes of reduced platelet production

A
  • Bone marrow could be suppressed by drugs, alcohol
  • Viral infections - can transiently cause low platelets
  • Hereditary bone marrow disorders -> either all cell line or just platelet
31
Q

What’s the name of the condition?

A

Thrombocytopenia with absent
radius

  • no radius (happen as part of the syndrome)
32
Q

What happens in Immune Thrombocytopaenia? (pathology)

A

Isolated thrombocytopenia -> only platelet count goes down

Pathology: Body recognises platelets as foreign body and gets rid of them

33
Q

Potential causes of Immune Thrombocytopenia

A
  • happens on its own
  • happens in association with infections e.g. HIV, malaria etc.
  • drugs: heparin, gold, quinine
  • Post-transfusion purpura -> delayed adverse reaction to a blood transfusion -> alloantibodies to foreign platlets (usually 5-12 days post-transfusion) -> rapid decline in platelet count
  • NAIT (neonatal alloimmune thrombocytopenia) -> passed through the placenta from mum to foetus (inherited platelet antigens)
34
Q

Diagnosis of Immune Thrombocytopenia

A
  • no diagnostic tests
  • exclusion (to investigate for other potential causes)
35
Q

When do we start to treat Immune Thrombocytopenia?

A

whether we start to treat or not - depends on platelet levels

if it is 80 that’s fine as should not cause any problems; if it is 20 - we do treat

36
Q

Drugs used in treatment of Immune Thrombocytopenia

A
  • steroids -> to induce immunosuppression -> so to reduce production of alloantibodies
  • IVIg -> immunoglobulin -> donor antibody given and saturates all the receptors on the spleen - > so platelets with antibodies attached to them not able to bind (for destruction)
  • Rituximab -> anti CD20 antibody -> stops from producing antibodies
  • Splenectomy -> so platelets with antibodies attached cannot be destroyed

- TPO-receptor agonist -> new approach, drug stimulating bone marrow to produce new platelets (thrombopoietin is platelet equivalent of erythropoietin EPO) -> producing more of platelets by putting bone marrow into overdrive to produce lots of platelets and to outnumber the antibodies that were produced

37
Q

What (other than autoimmune) conditions may lead to platelet destruction?

A
  • DIC - consumption of coagulation factors
  • TTP/HUS - rare hematological endothelial disorders -> platelet aggregation within vessels
  • Heart Bypass
  • Cardiopulmonary Bypass
  • Spleen is overactive -> getting rid of platelets
38
Q

What is defective/abnormal in ‘qualitative’ platelet disorder?

A
  • defective glycoproteins
  • abnormalities of platelet granules
  • drugs
  • haematological disorders
39
Q

What is deficient in vitamin K deficiency?

A

Vitamin K deficiency -> reduced production of: II, VII, IX, X, C and S

40
Q

What group of patients is at increased risk of vitamin K deficiency?

A

*may happen in hospitalised/ICU patients due to lack of adequate nutrient

41
Q

What may vitamin K cause in the newborn?

A

Vitamin K may cause hemorrhagic disease of a newborn (HDN) *therefore babies get vitamin K at birth to reduce their risk of bleeding

HDN - coagulation disturbance caused by vitamin K deficiency

42
Q

Management of vitamin K deficiency

A
  • vitamin K
  • in active bleeding -> vitamin K and fresh frozen plasma (ready coagulation factors)
43
Q

What is seen on Ix in vitamin K deficiency?

A
44
Q

What is Scurvy?

A

Scurvy -> Vitamin C deficiency -> problems with collagen (vessels affected) -> bleeding from them

45
Q

DIC

  • what happens?
  • causes
A
46
Q

Pathophysiology of Acquired Haemophilia

A

-it is not inherited

Pathology: Autoantibody (IgG) produced against factor VIII -> body gets rid of their own factor VIII

*it is spontaneous development of autoantibodies in someone who normally used to produce factor VIII

47
Q

Diagnosis of Acquired Haemophilia

A
  • very long aPTT
  • no correction in aPTT with mixing studies (so does not get better if somebody else’s plasma is put there -> as antibodies will destroy someone else’s factors)
48
Q

What to do if we see long aPTT?

A

If long aPTT is seen and we cannot see obvious explanation -> ask specialist (do not ignore

someone sitting on the ward with big bruises and massive aPTT)

49
Q

Treatment of Acquired Haemophilia

A
  • Factor VIII Inhibitor Bypassing Activity
  • Novo-Seven -> recombinant factor VIIa
  • steroids
  • Rituximab
  • DDAVP - desmopressin

Y3 Lecture week III (11 decks)

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