Polycythemia Flashcards
What is polycythemia?
Increase in haematocrit red cell count and haemoglobin concentration.
Can be relative due to low plasma volume or absolute
What is the key epidemiology of polycythemia?
Median age in 55-60yrs but can occur at any age
What are the causes of relative polycythemia?
Inc due to low plasma volume:
Dehydration
Chronic alcohol intake
Excess diuretic use
Pyrexia
Diarrhoea and vomiting
‘Stress polycythemia’
Gaisbock syndrome - HTN in young men, smokers, reduces plasma volume
What are the key causes of primary polycythemia?
Excess uncontrolled erythrocytosis independent of EPO -> JAK2 mutations.
Commonly polycythaemia rubra vera
What are the key causes of secondary polycythemia?
Driven by excess EPO
Chronic hypoxia such as COPD
Anabolic steroid use
Renal neoplasms
CKD (reduced EPO clearance)
Cyanotic heart disease
High affinity haemaglobinopathies
What are the key signs and symptoms of polycythemia?
Fatigue
Tension headache
Visual disturbance
Pruritus
Erythromelalgia
Arterial thrombosis
Venous thrombosis
Haemorrhage
Increased risk of gout
Facial redness on examination
Splenomegaly
Hypertension
Peptic ulceration
What are the specific features of primary polycythemia?
Hyperviscosity symptoms: chest pain, myalgia, weakness, headache, blurred vision, loss of concentration
Ruddy complexion
Splenomegaly
What are the key investigations for polycythemia?
Bedside - pulse oximetry
Bloods - FBC (raised haematocrit, rbcs, hb, raised/norm wbc/platelets, low-normal plasma volume)
Renal function - raised urate
Vitamin B12 - raised
EPO - low or high
Other: JAK2 mutation, bone marrow biopsy (hypercellular), abdo ultrasound (spleen, kidenys and liver)
What is the target haematocrit in the treatment of polycythemia?
Primary = <45%
Secondary = <55%
What is the treatment plan for polycythemia?
Venesection - risk of iron deficiency anaemia
In polycythemia rubra vera - also aspirin 75mg daily, and cytoredcutive therapy to suppress EPO (Hydroxcarbamide or interferon in young patients)
