This is an updated guideline on the diagnosis and management of polycythaemia vera (PV) from the British Society for Haematology. It was published in Nov 18. PV is the same as polycythaemia rubra vera and PCV.
Much of this is beyond what we need, but it outlines how we should be approaching a patient with raised haematocrit, which is useful.
If (like me) your understanding of PV is a bit sketchy, then patient.co.uk has a good reminder. In short, PV is a clonal haematological malignancy. It is caused by a mutation in a single haematopoietic stem cell. The JAK2 gene is mutated in nearly all PV.
What should trigger us to investigate further?
Patients with a persistently raised haematocrit. Haematocrit has been shown to be a better way of identifying patients than using haemoglobin levels (which is what old criteria were based on).
- Males > 0.52
- Females > 0.48
What should we cover in our initial assessment?
Drugs (both prescribed and recreational):
- Growth Hormone
Secondary cause symptoms
- Chronic lung disease
- Cyanotic heart disease
- Sleep apnoea / obesity
- Renal disease
- Oxygen saturations (SaO2 < 92% is associated with erythrocytosis). Beware the fact that CO poisoning, sleep apnoea and abnormal haemoglobins can give a spuriously raised SaO2 level.
- Features of the related conditions above.
What other initial investigations should be done?
- FBC and film
- Bone profile (a parathyroid tumour can cause secondary erythrocytosis)
- EPO (I would guess this would be done in secondary care normally).
- JAK2 analysis (in secondary care).
Other investigations may be needed if the cause is not obvious (eg bone marrow biopsy, USS abdo, CT scans etc). A lot of these will be done in secondary care.
What other causes of erythrocytosis are there?
Congenital EPO mutations.
Acquired PV. This can be driven by hypoxia (central or renal), pathological EPO production, drug induced, alcohol induced, post-renal transplant or idiopathic erythrocytosis.
Central hypoxia causes:
- Chronic lung disease.
- Right to left cardiopulmonary shunts.
- CO poisoning.
- Hypoxic states - eg sleep apnoea / altitude.
Local renal hypoxia causes:
- Renal artery stenosis.
- End stage renal failure.
- Renal cysts (eg polycystic kidney disease).
Pathological EPO production is caused by the following tumours:
- hepatocellular carcinoma.
- renal cell carcinoma.
- cerebellar haemangioma.
- parathyroid tumours.
- uterine leiomyoma.
- Testosterone / androgen preparations.
- Growth hormone
Management of PV
Most of the morbidity of PV is caused by thromboembolic events. Management will largely be by the haematologists.
- All patients should be given aspirin.
- Maintain a target haematocrit (eg using venesection).
- Manage other diseases related to thromboembolic risk (eg hypertension, diabetes, hyperlipidaemia, smoking).
- Cyt0reductive treatments will be used in some patients.