Thrombocytopenia Flashcards
(28 cards)
What is thrombocytopenia?
Low platelet count
What is the normal platelet count?
150-450 x 10^9/L
How can the causes of low platelet count be split?
Problems with production or destruction
What can reduced platelet production occur with?
Certain viral infections (EBC, CMV, HIV), B12 deficiency, folic acid deficiency, liver failure, leukaemia, myelodysplastic syndrome, chemotherapy
What can increased platelet destruction occur with?
Medications (eg. sodium valproate and methotrexate), alcohol, ITP, thrombotic thrombocytopenic purpura, heparin-induced thrombocytopenia, haemolytic uraemic syndrome
How can it be diagnosed?
Mild thrombocytopenia can be asymptomatic and found incidentally on a FBC
How does thrombocytopenia present?
Platelet counts below 50x10^9 ⇒ easy bruising and prolonged bleeding times, nosebleeds, bleeding gums, heavy periods, easy bruising, haematuria, rectal bleeding
What can platelet count below 10x10^9 lead to?
They’re at high risk of spontaneous bleeding, particularly concerning are: intracranial haemorrhage, GI bleeding
What are some differentials for abnormal or prolonged bleeding?
Thrombocytopenia, Von Willebrand disease, haemophilia A and B, DIC (usually secondary to sepsis)
What is ITP also called?
Autoimmune thrombocytopenic purpura, idiopathic thrombocytopenia purpura, and primary thrombocytopenia purpura
These all refer to the same condition
What is ITP?
A condition where antibodies are created against platelets, leading to their destruction and a low platelet count (thrombocytopenia), isolated low platelet count with normal bone marrow in the absence of other causes of low platelets
How does ITP characteristically present?
Purpura, which are non-blanching skin lesions caused by bleeding under the skin, petechiae, bleeding (eg. epistaxis)
Difference between timing of presentation in children and adults?
Children: acute thrombocytopenia that may follow infection or vaccination; adults tend to have a more chronic condition
Investigations for ITP?
Blood film
What does the care for ITP involve?
Monitoring platelet count, controlling BP, suppressing menstrual periods
Management options for ITP?
Oral prednisolone first line, IV immunoglobulins, thrombopoietin receptor agonists (eg. avatrombopag), Rituximab (MCA that targets B cells), splenectomy (less commonly used)
How does Rituximab work?
Rituximab is a MCA that targets the CD20 proteins on the surface of B cells, by attacking B cells and reducing their numbers, it reduces the production of the antibodies that are responsible for autoimmune disease
What is TTP?
Condition where tiny thrombi develop throughout the small vessels, using up platelets, described as a microangiopathy
What does TTP cause?
Thrombocytopenia, purpura, tissue ischaemia and end organ damage
Features of TTP?
Fever, neurological signs (microemboli), MAHA, renal failure, thrombocytopenia
Why do thrombi develop in TTP?
Due to a problem with a specific protein called ADAMTS13
What does the ADAMTS13 protein normally do?
Inactivate VWB factor, reduces platelet adhesion to vessel walls, reduces clot formation
What can deficiency in the ADAMTS13 protein be due?
An inherited genetic mutation (hereditary), autoimmune disease, where antibodies are created against the protein (acquired)
Treatment for TTP?
Guided by haematologist, plasma exchange, steroids, rituximab
