✅ Testosterone has a dose-dependent stimulating effect on erythropoiesis. Erythrocytosis or polycythemia is the most common dose-limiting effect of testosterone therapy.
✅ Prevalence of erythrocytosis 5% – 66% in testosterone-treated hypogonadal cis men, 11.5% in testosterone-treated trans men.
✅ Highest risk of erythrocytosis with injectable testosterone therapy. Biggest increase in the first 3 months to 1 year.
✅ Treatment options including stopping the testosterone therapy and reinitiating at a lower dose when the hematocrit normalizes, or instituting phlebotomy while continuing testosterone therapy.