2.2 Platelet disorders

Question 1

What characterises a drug rash?

Answer 1

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

Question 2

define petechiae, purpura, ecchymosis

Answer 2

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

Question 3

define petechiae, purpura, ecchymosis

Answer 3

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

Question 4

What are the symptoms of Henoch-Schonlein syndrome?

Answer 4

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

Question 5

Define purpura

Answer 5

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

Question 6

What are the usual underlying reasons for purpura

Answer 6

secondary platelet disorders

primary thrombocytopenic purpura

Question 7

What are the characteristics of immune thrombocytopenic purpura?

Answer 7

Thrombocytopenia (Plt)

Question 8

what is the pathogenesis of ITP?

Answer 8

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

Question 9

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

Answer 9

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

Question 10

What is the common polymorphism present in children with ITP?

Answer 10

FcGamma RIIIB

Question 11

What is the presentation of ITP

Answer 11

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

Question 12

What is the lab diagnosis of ITP?

Answer 12

Plt

Question 13

When would you do a bone marrow biopsy in ITP?

Answer 13

Age

Question 14

What is the usual course of treatment for ITP?

Answer 14

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

IVIG AT MOST POINTS

Question 15

When would you give a platelet transfusion in ITP?

Answer 15

Only with intracranial haemorrhage (give with IVIG and steroids)

Question 16

What is the usual course of treatment for ITP?

Answer 16

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)

Question 17

When would you give a platelet transfusion in ITP?

Answer 17

Only with intracranial haemorrhage (give with IVIG and steroids)

Question 18

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

Answer 18

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

Give is thrombocytopenia > 3 weeks or recurrent

Question 19

What is the role of IVIG treatment in ITP?

Answer 19

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

Question 20

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

Answer 20

Anti D therapy

Question 21

When is splenectomy indicated in ITP?

Answer 21

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

Anti platelet antibodies are formed in the spleen

Question 22

What is the treatment for intracranial bleeding in ITP?

Answer 22

Splenectomy
Plt transfusion
IVIG
Emergency craniotomy if neurological

Question 23

What is Rituximab and how does it work?

Answer 23

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

Question 24

What are the immunosuppressive drugs available for ITP?

Answer 24

Cyclophosphamide
Azathiprime
Cyclosporin

Question 25

What is Danazol

Answer 25

Steroid for ITP

Question 26

What is the new line of therapy for ITP?

Answer 26

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

Question 27

What are the risk factors for progression to chronic ITP?

Answer 27

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

Question 28

What is the presentation of - Thrombotic thrombocytopenia purpura?

Answer 28

Microangiopathic anaemia 
Sever thrombocytopenia 
Neurological symptoms 
Renal failure
Fever

Question 29

What is the pathophysiology of Thrombotic thrombocytopenia purpura?

Answer 29

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

Question 30

What is the diagnosis of Thrombotic thrombocytopenia purpura

Answer 30

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

Question 31

What is the diagnosis of Thrombotic thrombocytopenia purpura

Answer 31

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

Question 32

What is the treatment for Thrombotic thrombocytopenia purpura?

Answer 32

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