erythrocytosis: [ ĕ-rith″ro-si-to´sis ] increase in the total red blood cell mass secondary to any of a number of nonhematogenic systemic disorders in response to a known stimulus (secondary polycythemia ), in contrast to primary polycythemia (polycythemia vera). stress erythrocytosis an apparent polycythemia seen in active, anxiety-prone …

https://medical-dictionary.thefreedictionary.com/erythrocytosis