When haematopoesis goes wrong Flashcards
What are myeloid proliferative neoplasms?
A group of diseases of the bone marrow, in which excess cells are produced.
Why do myeloproliferative neoplasms occur?
Genetic mutations in the precursors of myeloid lineage in bone marrow
4 main types of myeloproliferation neoplasms
Polycythaemia vera- excess rbcs
Essential thrombocythaemia- - excess production of megakaryocytes leading to excess platelets
Primary myeliofibrosis— leads to pancytopenia
Chronic myeloid leukaemia- excess granuloma tea
Polycythaemia
Disease where the volume percentage of erythrocytes in the blood in males is greater than 52% or 48% in females
What does polycythaemia arise from?
Myeloproliferative neoplasms in the bone marrow
Types of polycythaemia
Relative- there is a decrease in plasma volume so an increase in the relative percentage of red blood cells could be due to dehydration
Absolute- there is an increase in the number of rbcs
Types of absolute polycythaemia
Primary- originates in the bone marrow- polycythaemia bone marrow
Secondary- caused by increased levels of erythropoietin
Types of absolute secondary polycythaemia
Physiological response to hypoxia- normal
Abnormal production
Reasons for absolute secondary polycythaemia- physiological response
High altitude
Chronic lung disease
Reasons for absolute secondary polycythaemia- abnormal production
Renal carcinoma
Renal artery stenosis
Causes of polycythaemia vera
Most cases are caused by a genetic mutation of the gene coding for Janus kinase 2 (JAK2)- a tyrosine kinase which normally works in response to erythropoietin
Clinical features of polycythaemia vena
Stickier blood Thrombosis Haemorrhage Headache and dizziness Excess body Pruritus Splenomegaly Gout Arthritis
Treatment of polycythaemia vena
Take blood to keep the haematocrit below 45%- although if the patient has poor tolerance to venesection may use hydroxycarbamide
May also use aspirin- anti platelet drug
Thrombocytosis
Increase in platelet count compared to normal range of a person of the same gender and age
Reasons for thrombocytosis
Reaction to infection and inflammation
Result from myeloproliferative neoplasm - known as essential thrombocythaemia
The splenic platelets can also be redistributed to the blood stream
What is essential thrombocytosis?
Chronic blood cancer- over production of platelets by megakaryocytes in the bone marrow.
Common symptoms of essential thrombocytosis
Numbness in extremities Thrombosis Disturbances in hearing and vision Headaches Burning sensation in the hands or feet
Treatments for thrombocytosis
Low risk for bleeding- aspirin
High risk for bleeding- hydoxycarbamide
Thrombocytopenia
Low level of platelets
Reasons for thrombocytopenia
Inherited thrombocytopenia,
Acquired thrombocytopenia- decrease in platelet production, increased combustion of platelets or increased destruction of platelets
Symptoms of acquired thrombocytopenia
Bleeding gums, nose bleeds, heavier/ long periods, bruising and petechiae,
Immune thrombocytopenia purpura
An autoimmune disease- isolated thrombocytopenia- can be acute or chronic
Reasons for decreased platelet production
B12 or folate deficiency Acute leukaemia Aplastic anemia Liver failure- leading to decreased production of thrombopoetin Sepsis Cytotoxic chemotherapy
Reasons for increased platelet consumption
Massive haemorrhage
Disseminated intravascular coagulation
Thrombotic thrombocytopenia purpura
