When would you initiate chronic therapeutic phlebotomy in a patient with erythrocytosis secondary to a high hemoglobin-oxygen affinity hemoglobinopathy?

The large majority of patients with high oxygen affinity hemoglobinopathy do not require therapeutic phlebotomy. There is a subset of patients who develop symptoms (generally these are non-specific such as headache) or complications such as thrombosis. There seems to be no correlation between hemato...