Dr Chris Hillis is an assistant professor in the Division of Oncology at McMaster University and hematologist at the Juravinski Hospital and Cancer Centre.
How to manage patients with secondary polycythemia? Should we perform phlebotomies or administer antiplatelet treatment?
Chris Hillis, MD, MSc: It depends on the cause of secondary polycythemia. In a patient who has cyanotic congenital heart disease or a high-oxygen-affinity hemoglobin, this is an important compensatory mechanism to maintain oxygen delivery for these patients. Phlebotomizing can actually cause harm if you are too aggressive with your phlebotomies.
As a general rule, in secondary erythrocytosis we will only phlebotomize [those] with symptoms of hyperviscosity, such as headaches, shortness of breath, or blurred vision. We would definitely not phlebotomize these patients to such aggressive targets as we would [use] in patients with polycythemia vera (PV). Our typical phlebotomy target would be a hematocrit of 52%, and we would very rarely start phlebotomizing until the hematocrit reached 55% or 56%.
Antiplatelet treatment in these patients is typically guided by the cause and comorbidities. If you have a patient who is elderly and has coronary artery disease or is at very high risk, you may use antiplatelet agents. There is no randomized control trial evidence to guide what to do in these patients, so typically in patients over 50 we will consider adding antiplatelet therapy and in those under 50 it will really be on a case-by-case basis.