Thrombocytopenia Flashcards
What is thrombocytopenia?
Low platelet count
What is the normal platelet count range?
150-450 x 10^9/L
What are the production problems that lead to thrombocytopenia?
Sepsis B12 and folate deficiency Liver failure - causes failure of thrombopoietin production in the liver Leukaemia Myelodysplastic syndrome
What are the destruction problems that lead to thrombocytopenia?
Medications Alcohol Idiopathic thrombocytopenic purpura Thrombotic thrombocytopenic purpura Heparin induced thrombocytopenia Haemolytic uraemic syndrome
Which medications can lead to thrombocytopenia?
Methotrexate Sodium valproate Isotretinoin Anti-histamines Proton pump inhibitors
Presentation of thrombocytopenia
Mild thrombocytopenia incidentally picked up on FBC
Platelet count <50 x10^9/L - spontaneous bruising, prolonged bleeding times - nosebleeds, bleeding gums, heavy periods, easy bruising or blood in urine/stools
Platelet count <10x10^9/L = high risk for spontaneous bleeding, spontaneous intracranial haemorrhage or GI bleeds
Differential diagnosis of abnormal/ prolonged bleeding
Thrombocytopenia Von Willebrand Disease Haemophilia A Haemophilia B Disseminated intravascular coagulation (usually secondary to sepsis)
Immune thrombocytopenic purpura is also known as?
Autoimmune thrombocytopenic purpura
Primary thrombocytopenic purpura
Idiopathic thrombocytopenic purpura
What is the pathophysiology of ITP?
Antibodies form against platelets –> destruction of platelets –> low platelet count
Management of ITP?
Prednisolone
IV immunoglobulins
Rituximab = monoclonal Ab against B cells
Splenectomy
What is important in patient education of ITP?
That platelet count requires monitoring Need to know concerning signs of bleeding e.g. persistent headaches and melaena When to seek help Carefully controlling BP Suppressing menstrual periods
What is thrombotic thrombocytopenic purpura?
Clots develop throughout the small vessels of the body - using up platelets and causing thrombocytopenia
It’s a microangiopathy because it affects the small vessels
What is the pathophysiology?
Clots form because of a defect in the ADAMTS13 protein
What is the normal function of ADAMTS13 protein?
Inactivates von Willebrand factor, reduces platelet adhesion to vessel walls and clot formation
What happens in TTP?
Shortage of ADAMTS13 –> von Willebrand overactivity –> clot formation in small vessels –> platelets used up –> thrombocytopenia
How does TTP cause additional haemolytic anaemia?
The microclots in the small vessels –> break up RBCs –> haemolytic anaemia
What are the causes of deficiency in ADAMTS13?
Inherited genetic mutation OR
Autoimmune disease where antibodies are created against the protein
Treatments of TTP?
Plasma exchange
Steroids
Rituximab
guided by haematologist
What is heparin induced thrombocytopenia?
Thrombocytopenia by antibodies forming against platelet factor 4 on platelets which occurs as a result of exposure to heparin
How does the HIT PF4/heparin antibodies cause thrombocytopenia?
HIT antibodies bind to platelets and activate clotting mechanisms –> causing hypercoagulable state –> thrombosis –> they also break down platelets and cause thrombocytopenia
So HIT causes?
Pts on heparin with thrombocytopenia form unexpected clots
Diagnosis of HIT?
Testing for HIT antibodies in the patients blood
Management of HIT
Stopping heparin
Anticoagulation with an alternative anticoagulant guided by a specialist