2.2 Platelet disorders Flashcards by Sarah Ellis

What characterises a drug rash?

A rash that usually starts within 2 weeks of taking new medication and begins as discrete red spots that spread, covering large areas of the body

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define petechiae, purpura, ecchymosis

Petechiae: 1-5mm
Purpura: 5-10mm
Ecchymosis: >10mm

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define petechiae, purpura, ecchymosis

Petechiae: 1-5mm
Purpura: 5-10mm
Ecchymosis: >10mm

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What are the symptoms of Henoch-Schonlein syndrome?

GI pain and bleeding (85%), fever (75%), arthralgia (75%), especially involving the knees and ankles, glomerulonephritis (40%)

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Define purpura

the appearance of red or purple discolorations on the skin, caused by bleeding underneath the epidermis
- Petechiae 1 cm

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What are the usual underlying reasons for purpura

secondary platelet disorders

primary thrombocytopenic purpura

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What are the characteristics of immune thrombocytopenic purpura?

Thrombocytopenia (Plt)

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what is the pathogenesis of ITP?

Platelet autoantibodies (IgG) result in the premature removal of platelets from the circulation by macrophages.

Antibody is usually directed against antigen sites on glycoprotein IIb-IIIa or Ib complex

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What are the different types of ITP and how are they characterised?

Acute: Plt return to normal 3 weeks - 6 months and no relapse
Chronic: low plt >6 months
Recurrent: Plt decreases after return to normal

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What is the common polymorphism present in children with ITP?

FcGamma RIIIB

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What is the presentation of ITP

Cutaneous manifestations: petechial haemorrhage, easy bruising
Mucosal bleeds
Internal organ bleeding
(no pallor or splenomegaly usually)

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What is the lab diagnosis of ITP?

Plt

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When would you do a bone marrow biopsy in ITP?

Age

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What is the usual course of treatment for ITP?

none if Plt >30,000/cm 
No contact sports 
no IM injections 
Observes (weekly bloods) 
Depo provera (females)

IVIG AT MOST POINTS

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When would you give a platelet transfusion in ITP?

Only with intracranial haemorrhage (give with IVIG and steroids)

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What is the usual course of treatment for ITP?

IVIG AT MOST POINTS
Steroids
Anti D therapy

Management:
none if Plt >30,000/cm 
No contact sports 
no IM injections 
Observes (weekly bloods) 
Depo provera (females)

When would you give a platelet transfusion in ITP?

Only with intracranial haemorrhage (give with IVIG and steroids)

What is the role of steroids in ITP and when would you give it?

Decrease phagocytosis of antibody coated platelets, decrease antibody production and increase vascular stability

Give is thrombocytopenia > 3 weeks or recurrent

What is the role of IVIG treatment in ITP?

Decreases autoantibody production by blocking the Fc receptor. This is the treatment of choice

What treatment do you use in acute Rh + non splenectomy patients?

Anti D therapy

When is splenectomy indicated in ITP?

Any patient with uncontrolled ITP who has failed to respond to steroids/IVIG

Anti platelet antibodies are formed in the spleen

What is the treatment for intracranial bleeding in ITP?

Splenectomy
Plt transfusion
IVIG
Emergency craniotomy if neurological

What is Rituximab and how does it work?

A chimeric monoclonal antibody against the protein CD20. This causes phagocytosis of anti-CD20 coated B cells

What are the immunosuppressive drugs available for ITP?

Cyclophosphamide
Azathiprime
Cyclosporin

What is Danazol

Steroid for ITP

What is the new line of therapy for ITP?

TPO mimetics which will stimulate bone marrow receptor for proliferation of megakaryocytes to then produce more megakaryocytes

What are the risk factors for progression to chronic ITP?

purpura > 2-4 weeks prior to diagnosis Female > 10 Higher platelet count at presentation

What is the presentation of - Thrombotic thrombocytopenia purpura?

``` Microangiopathic anaemia Sever thrombocytopenia Neurological symptoms Renal failure Fever ```

What is the pathophysiology of Thrombotic thrombocytopenia purpura?

There is a deficiency of vWF cleaving protein ADAMTS13. This causes unusually large vWF that would usually be broken down ot remain anchored to the cells causing platelet aggregation and microvascular thrombosis Low Hb, Low platelets, clotting

What is the diagnosis of Thrombotic thrombocytopenia purpura

Coombs negative haemolysis with fragmentation Thrombocytopenia Renal failure Neurologic symptoms ranging from headache to seizures and coma Symptoms often fluctuate Fever not frequent

What is the diagnosis of Thrombotic thrombocytopenia purpura

Coombs negative haemolysis with fragmentation Thrombocytopenia Renal failure Neurologic symptoms ranging from headache to seizures and coma Symptoms often fluctuate Fever not frequent

What is the treatment for Thrombotic thrombocytopenia purpura?

Plasma exchange (supplies missing ADAMTS13 and removes antibodies and large vWF) - usually given with corticosteroids, imunosuppressive drugs EXCEPT in post diarrhoeal HUS in childern and following chemo and bone marrow transplant