2.2 Platelet disorders Flashcards
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
define petechiae, purpura, ecchymosis
Petechiae: 1-5mm
Purpura: 5-10mm
Ecchymosis: >10mm
define petechiae, purpura, ecchymosis
Petechiae: 1-5mm
Purpura: 5-10mm
Ecchymosis: >10mm
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%)
Define purpura
the appearance of red or purple discolorations on the skin, caused by bleeding underneath the epidermis
- Petechiae 1 cm
What are the usual underlying reasons for purpura
secondary platelet disorders
primary thrombocytopenic purpura
What are the characteristics of immune thrombocytopenic purpura?
Thrombocytopenia (Plt)
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
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
What is the common polymorphism present in children with ITP?
FcGamma RIIIB
What is the presentation of ITP
Cutaneous manifestations: petechial haemorrhage, easy bruising
Mucosal bleeds
Internal organ bleeding
(no pallor or splenomegaly usually)
What is the lab diagnosis of ITP?
Plt
When would you do a bone marrow biopsy in ITP?
Age
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
When would you give a platelet transfusion in ITP?
Only with intracranial haemorrhage (give with IVIG and steroids)
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
