Polycythaemia Vera Flashcards
what is polycythaemia vera?
a myeloproliferative disorder characterised by the excess production of erythrocytes
what is polycythaemia?
when excess red blood cells are produced resulting in a raised haemoglobin concentration and haematocrit
what causes polycythaemia vera?
a mutation in the JAK2 (janus kinase 2) gene
what are the causes of secondary polycythaemia?
- chronic hypoxia (i.e. secondary to smoking or chronic lung disease)
- local renal hypoxia (e.g renal artery stenosis)
- excess erythropoietin (EPO) production (i.e. secondary to EPO-secreting tumours)
which syndrome is considered to be a risk factor for polycythaemia vera?
budd-chiari syndrome
what are the symptoms of polycythaemia vera?
- headache
- dizziness
- myalgia
- fatigue
- tinnitus
- pruritus
- erythromelalgia
- blurred vision
- dyspepsia
- gout
a third of patients with polycythaemia vera present with what?
thrombosis (e.g. stroke, MI, DVT, PE, or budd-chiari syndrome)
what are the findings on examination for polycythaemia vera?
- a ‘ruddy’ complexion
- splenomegaly
- abdominal mass (e.g. uterine, renal, or hepatic tumours which can secrete EPO)
- hypertension
what are the criteria used to define polycythaemia?
- M: Hb >185 g/L +/- Hct >0.52
- F: Hb >165 g/L +/- Hct >0.48
- RCM > 25%
what is apparent polycythaemia?
- if the patient is dehydrated, apparent polycythaemia may be present in which the Hb/Hct is raised because of a reduced plasma volume
- these patients will have a normal RCM
what are the investigations for polycythaemia vera?
- FBC
- blood film
- U&Es
- LFTs
- serum ferritin
- ABG
- serum EPO
- JAK 2 V617F mutational analysis
what does the level of serum EPO suggest in the context of polycythaemia?
suppressed levels suggest polycythaemia vera whilst raised levels in the context of polycythaemia suggest a secondary cause; inappropriate EPO production and the possibility of an EPO-secreting tumour
what investigation may be used to distinguish polycythaemia vera from secondary polycythaemia?
- bone marrow biopsy
- in polycythaemia, a biopsy may show hypercellularity, increased erythropoiesis, granulopoiesis and megakaryopoiesis, and variable megakaryocyte size
what is the management of polycythaemia vera?
- cardiovascular optimisation (e.g. hyperlipidaemia, diabetes)
- intermittent, long-term phlebotomy (Hct <0.45)
- low-dose aspirin
- cytoreductive therapy (e.g. hydroxycarbamide/interferon-alpha)
what are the long-term complications of polycythaemia vera?
- ischaemic stroke
- MI
- PE
- myelofibrosis/AML
- gastrointestinal haemorrhage
- budd-chiari syndrome
