05/08/2026
If you’re on TRT, you’ve probably heard that your hematocrit (HCT) can sometimes get elevated. We'd estimate that it occurs in roughly ~15-20% of our patients.
The common advice?
PANIC!
But hold on—is an elevated hematocrit on TRT the same thing as having a disease? Not necessarily.
Why does it happen?
Testosterone stimulates Erythropoietin (EPO) in the kidneys and suppresses Hepcidin, which tells your body to increase red blood cell production. It’s a very common side effect of therapy, but "high" doesn't always mean "danger."
TRT causes secondary erythrocytosis (more red cells). This is fundamentally different from Polycythemia Vera, which is a genetic bone marrow disease that increases ALL OF YOUR CELLS ("polycythemia"). PV increases RBCs, WBCs, platelets, you name it.
Again, TRT only increases red blood cells, but only in a fraction of patients who are on TRT.
Hydration is Key: Hematocrit is a percentage of red cells to plasma. If you’re even slightly dehydrated during your blood draw, your Hematocrit will look artificially high.
The "Altitude" Effect: People living in high altitudes (like Denver) naturally have hematocrit levels in the mid-50s. Their bodies adapt, and their hearts don't just stop.
The Bottom Line: Don't treat a number; treat the patient. Always consult with a provider who understands the nuances of hormone optimization before rushing to the donation center.
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