What is erythrocytosis and why does it matter on TRT?
Erythrocytosis is elevated red cell mass. It is the most common TRT side effect requiring intervention. Provider review halts dose escalation at HCT 52% and triggers phlebotomy at 54%.
Full answer
Erythrocytosis is an elevated red blood cell mass, measured operationally as hematocrit. Testosterone stimulates erythropoietin and red-cell production, making erythrocytosis the most common TRT side effect requiring dose adjustment or therapeutic intervention. Excessive elevation raises blood viscosity and cardiovascular event risk. oMeds provider review requires CBC at baseline and on recalibration cadence in all Hormone Optimization patients; halts dose escalation when hematocrit approaches 52%; and triggers therapeutic phlebotomy at 54%. Risk factors include high-dose injectable formulations, smoking, sleep apnea, and high altitude.
Educational. Not a substitute for individualized provider review.
- Hemoglobin — Primary source · oMeds
- Reviewed by Dr. Laura Purdy, MD, MBA · Clinical Director, oMeds · Last reviewed 2026-05-29