Maintenance therapy

Once the acute erythrocytosis has been reduced to acceptable levels - PCV less than 0.49 for males and 0.45 for females - maintenance treatment must be considered.

Venesection at six-monthly intervals suffices in most patients; a minority require venesection monthly or even more frequently. It is the latter group who should be considered for anti-myeloproliferative drug treatment as they have a high risk of thrombosis in the first 5-7 years after diagnosis.

The following measures might also be considered:

• maintaining fluid intake to minimise haemoconcentration
• prophylactic allopurinol
• antihistamines to relieve pruritus