@lesters_labs's thick blood claims on TRT, fact-checked

What does this video actually claim?

Lester Buhrmann claims testosterone replacement therapy (TRT) causes thick blood by raising hematocrit levels, and suggests hormones like progesterone and estrogen can fix this by influencing hepcidin, a protein that regulates iron absorption. He's basically arguing you can manipulate your blood thickness through hormonal tweaks instead of the standard approaches doctors typically use.

The video targets bodybuilders and biohackers on TRT who worry about elevated red blood cell counts. It's presented as a science-backed solution with multiple study citations.

Does the science support hepcidin manipulation?

The hepcidin connection is real but oversimplified. Hepcidin does regulate iron absorption and can influence red blood cell production, as shown in Ganz & Nemeth's 2015 review in Blood. Higher hepcidin levels reduce iron availability, which can theoretically lower hematocrit over time.

However, the hormone-hepcidin relationships Buhrmann cites are mostly from observational studies or animal research. The 2015 study by Lehtihet et al. (PMID: 26657863) did find progesterone increased hepcidin in postmenopausal women, but that's quite different from young men on TRT.

The estrogen studies he references show mixed results. Some found estrogen increased hepcidin, others showed decreases depending on timing and dose.

What's missing from this approach?

Buhrmann ignores the most proven methods for managing TRT-related polycythemia. Regular blood donation reduces hematocrit by 3-6 percentage points within weeks, according to multiple studies including work by Samiee-Rad et al. in 2019.

He also skips over dose optimization. Many men can lower their hematocrit simply by reducing testosterone dose or switching from injections to gels, which create less erythropoietin stimulation.

The video doesn't mention that most healthy men tolerate hematocrit levels up to 52-54% without problems. The obsession with driving it lower might be unnecessary for many people.

What should you actually know?

TRT does raise hematocrit in about 20-30% of men, typically by 2-5 percentage points above baseline. This happens because testosterone stimulates erythropoietin production in the kidneys, leading to more red blood cell creation.

If your hematocrit climbs above 52-54%, proven solutions include therapeutic blood donation every 8-12 weeks, dose reduction, or switching formulations. These approaches work reliably and quickly.

The hepcidin manipulation strategy might work in theory, but it's unproven in TRT patients. You'd be experimenting with additional hormones to solve a problem that has established solutions. That seems unnecessarily complicated for most people.