Thrombocytopenia Flashcards
Causes of thrombocytopenia
Problems with production: sepsis, B12/folate deficiency, liver failure (reduced thrombopoietin), leukaemia, myelodysplastic syndrome
Problems with destruction: medications (sodium valproate, methotrexate, isotrentinoin, antihistamines, PPIs), alcohol, ITP, TTP, HIP, HUS.
Presentation of thrombocytopenia
Mild: asymptomatic, incidentally found on FBC
Moderate: spontaneous bruising and prolonged bleeding times
Severe: high risk for spontaneous bleeding, ICH or GI bleeds
DDx of abnormal / prolonged bleeding
Thrombocytopenia
Haemophilia (A/B)
VWD
DIC
ITP pathophysiology & management
Antibodies against platelets form, causing an immune response resulting in the destruction of platelets and a low platelet count.
Rx: prednisolone, IV immunoglobulins, rituximab, splenectomy
Monitor platelet count and BP, suppression of periods may be necessary. Seek help if there are persistent headaches of meleana
TTP pathophysiology and management
Tiny blood clots develop throughout the small vessels, using up platelets resulting in thrombocytopenia & bleeding under skin (microangiopathy). This is due to an error with ADAMTS13 (inherited gene mutation / autoimmune disease) which usually inactivates VWF and reduces platelet adhesion to vessel walls and clot formation. Less protein = more VWF activity and formation of clots in small vessels. This uses up platelets resulting in thrombocytopenia. The clots in the vessels break up red blood cells leading to haemolytic anaemia.
Rx: plasma exchange, steroids and rituximab
HIT pathophysiology and management
Development of antibodies against platelets in response to heparin exposure. These target PF4 protein on platelets and activate clotting mechanisms, causing a hypercoaguable state leading to thrombosis, also causing breakdown of platelets causing thrombocytopenia.
Dx: testing for HIT antibodies
Rx: stop heparin, use an alternative anticoagulant.
