Haematology - thrombocytopenia Flashcards
What is thrombocytopenia?
Low platelets
Broadly what causes thrombocytopenia
Reduced production
Increased destruction
What can cause thrombocytopenia?
Reduced production:
- Sepsis
- B12/folate deficiency
- Liver failure causing reduced thrombopoeitin production in the liver
- Leukaemia
- Myelodysplastic syndrome
Increased destruction:
- Medications
- Alcohol
- Immune thrombocytopenic purpura
- Thrombotic thrombocytopenic purpura
- Heparin induced thrombocytopenia
- HUS
What medications can lower platelets?
Sodium valproate
Methotrexate
Isotretinoin
PPIs
Antihistamines
Presentation of thrombocytopenia
May be asymptomatic and an incidental finding
Easy or spontaneous bruising
Prolonged bleeding times
Nosebleeds
Bleeding gums
Heavy periods
Blood in urine/stool
Platelet counts below 10 x 109/L are high risk for spontaneous bleeding. Spontaneous intracranial haemorrhage or GI bleeds are particularly concerning.
Differential diagnosis of abnormal or prolonged bleeding
Thrombocytopenia (low platelets)
Haemophilia A and haemophilia B
Von Willebrand Disease
Disseminated intravascular coagulation (usually secondary to sepsis)
What is ITP?
Antibodies created against platelets.
Causes destruction of platelets and therefore low platelet count
Management options for ITP
Prednisolone
IVIG
Rituximab - a monoclonal antibody against B cells
Splenectomy
What is TTP?
Thrombotic Thrombocytopenic Purpura
This is a condition where tiny blood clots develop throughout the small vessels of the body using up platelets and causing thrombocytopenia, bleeding under the skin and other systemic issues.
These clots develop due to a deficiency in ADAMTS13 protein (this protein usually inactivates VWF and reduces clot formation)
Haemolytic anaemia - blood clots break up RBCs
What causes TTP?
An inherited genetic mutation
Or due to autoimmune disease where antibodies are created against ADAMTS13 protein
Treatment of TTP
Haematology specialist
May include plasma exchange, steroids and rituximab (a monoclonal antibody against B cells).
What is heparin induced thrombocytopenia?
Development of antibodies against platelets in response to heparin treatment.
(These heparin induced antibodies specifically target a protein on the platelets called platelet factor 4 (PF4). These are anti-PF4/heparin antibodies.)
The antibodies activate clotting cascade and cause hypercoagulable state.
They also break down platelets and cause thrombocytopenia.
How is HIT diagnosed?
Testing for serum HIT antibodies
Treatment of HIT?
Stopping the heparin
Using an alternative anticoagulant
