TRT and red blood cell increase: what the hematocrit data actually shows

What did @sexedtok actually say?

The creator explained that testosterone replacement therapy causes the body to produce more red blood cells, which raises hematocrit, defined accurately as "the percentage of your blood that's made up of red blood cells." They warned that elevated hematocrit makes blood "quote unquote thick," increasing clot risk, and that their clinic checks hematocrit every three months. That's a reasonable, plain-language summary of a real clinical concern. The framing is practical and patient-facing, not alarmist.

The video appears to come from a clinic setting, which gives it a grounded, educational tone. Nothing here is promotional or reckless. The core message, that high hematocrit on TRT needs monitoring, is sound. But a few details deserve more scrutiny before patients walk away thinking they fully understand the risk picture.

Does the science back this up?

Yes, mostly. Testosterone stimulates erythropoiesis through erythropoietin signaling, and elevated hematocrit on TRT is well-documented. The claim that this raises clot risk is biologically plausible, but the actual magnitude of that risk in men on monitored TRT is more contested than the video suggests.

A 2023 randomized controlled trial by Lincoff et al. in the New England Journal of Medicine (TRAVERSE trial) found no statistically significant increase in major adverse cardiovascular events in hypogonadal men on testosterone therapy versus placebo, though it did find a higher rate of pulmonary embolism in the testosterone group. Separately, Glueck et al. (2014, Clinical and Applied Thrombosis/Hemostasis) documented venous thromboembolism cases tied to TRT, often in men with underlying thrombophilia. So the risk is real, but it is not uniform across all patients. The video's framing, "blood clots are bad," is accurate but stripped of the nuance that most healthy, monitored men on appropriate doses do not experience these events.

What did they get wrong (or right)?

They got the fundamentals right. The hematocrit definition is correct. The mechanism, more testosterone drives more red blood cell production, is accurate. The three-month monitoring interval is consistent with Endocrine Society guidelines (Bhasin et al., 2018, Journal of Clinical Endocrinology and Metabolism), which recommend checking hematocrit at three and six months, then annually.

What's missing is a threshold. The video never mentions what "too high" actually means. Most clinicians flag concern at hematocrit above 52-54%, with some guidelines setting 54% as a hard stop for dose adjustment or phlebotomy. Without that number, patients leave with vague anxiety rather than actionable information. The video also skips viscosity entirely as a mechanism. "Thick blood" is not wrong, but the actual hemodynamic issue is increased blood viscosity reducing microvascular flow, which is distinct from simply having more red cells. That distinction matters for patients who want to understand their own labs.

What should you actually know?

If you are on TRT, hematocrit monitoring is not optional. It is a standard part of responsible prescribing. The Endocrine Society recommends withholding or reducing testosterone if hematocrit exceeds 54%, and therapeutic phlebotomy is sometimes used to bring levels down. Some clinicians also evaluate for sleep apnea, which independently raises hematocrit and is common in the same population seeking TRT.

The TRAVERSE trial (Lincoff et al., 2023, NEJM) is worth knowing about. It is the largest randomized trial of TRT cardiovascular outcomes to date. It did not show a spike in heart attacks or strokes, but it did show a pulmonary embolism signal. That is not a reason to panic, but it is a reason to be honest about what monitoring actually catches and what it does not. Hematocrit alone does not capture clotting factor changes or platelet activation. Patients with personal or family history of clotting disorders should have that conversation explicitly with their prescriber before starting TRT, not after a lab flag.