The most common silent problem on TRT is not gyno. It’s not hair loss. It’s not even the libido swings guys complain about online. It’s hematocrit creeping into dangerous territory while everything else looks fine — and most guys, including a lot of TRT clinics, don’t take it seriously enough.
I’ve been on testosterone replacement for over 10 years. I’ve written before about my TRT protocol broadly, but I want to drill down on this single issue because it’s the one that nearly took me out twice in the early years and that I see new TRT guys completely misjudge.
If you’re on TRT — clinic-prescribed or grey-market doesn’t matter — and you don’t know your hematocrit and red blood cell count from your last bloodwork, stop reading and pull up your labs. Numbers first.
What Hematocrit Is and Why TRT Pushes It Up
Hematocrit is the percentage of your blood volume that’s red blood cells. Normal range for adult men is roughly 41% to 53%. Women run lower because they don’t have testosterone driving erythropoiesis.
Testosterone is a powerful stimulus for red blood cell production. It signals the kidneys to release more erythropoietin (EPO), which tells the bone marrow to crank out more RBCs. Higher T = more RBCs = thicker blood.
Up to a point this is good. More red blood cells means more oxygen-carrying capacity, better endurance, faster recovery. This is part of why TRT makes you feel athletic again. But past about 52%, things start to get dangerous. Past 54%, your blood is essentially syrup. Risk of:
- Stroke
- Deep vein thrombosis
- Pulmonary embolism
- Heart attack from clot formation
- Hypertension that won’t respond to standard treatment
- Erectile dysfunction (ironic — too thick blood can’t perfuse the corpora cavernosa properly)
This isn’t theoretical. The cardiovascular events you hear about in the bodybuilding community — including some very public deaths in the last few years — are disproportionately driven by elevated hematocrit, not by the testosterone itself.
My Numbers — a cautionary tale
When I first started TRT in my early 30s, I was on 200 mg/week of testosterone cypionate, twice-weekly injections. Within 8 months my hematocrit was 56%. My GP at the time wasn’t a TRT specialist and didn’t flag it. I had the kind of subtle symptoms you don’t notice until you look back: morning headaches I assumed were dehydration, slightly red-flushed face, occasional dizziness when standing up fast, and worsening sleep.
I caught it almost by accident — running my own bloodwork before a planned trip. 56% hematocrit. RBC count of 6.2. Hemoglobin pushing 19 g/dL. Stroke territory.
I dropped my dose, donated blood twice in three weeks, and within two months I was back at 49% hematocrit and feeling clearer than I had in months. That experience built the protocol I’ve now run for nearly a decade.
The Protocol I’ve Run for 10 Years
Step 1 — Test every 3 months, no exceptions. Full CBC plus comprehensive metabolic plus lipid plus testosterone panel. The CBC is non-negotiable. My full TRT bloodwork guide covers everything you should be tracking, but for the hematocrit issue specifically you need: hematocrit, hemoglobin, RBC count, MCV, MCH, MCHC, RDW, and platelets.
Step 2 — Decide on your action thresholds in advance. Mine, after a decade of self-experimentation and discussion with hematology-trained docs:
- Below 50%: do nothing
- 50-52%: hydration push, optimize sleep, recheck in 6 weeks
- 52-54%: schedule a blood donation, recheck 4 weeks after
- Above 54%: donate immediately, lower TRT dose, recheck in 4 weeks
Step 3 — Donate blood every 8-12 weeks as a baseline. Even if my hematocrit is in range, I donate roughly every 10 weeks. This keeps me well below threshold and provides the side benefit of reducing iron stores, which is itself probably a longevity intervention. (Excess iron is associated with oxidative stress and cardiovascular disease in men — we don’t menstruate, so we accumulate iron our whole adult lives unless we actively offload it.)
Step 4 — Split your dose. Daily or every-other-day micro-doses of testosterone produce flatter blood levels and less aggressive RBC production than once-weekly or twice-weekly larger injections. I went from 100 mg twice a week to 30 mg every other day in 2019 and my baseline hematocrit dropped about 2 percentage points just from that protocol change, with no change in total weekly dose.
Step 5 — Hydration is not optional. Most guys are chronically dehydrated. On TRT in a hot climate, that dehydration concentrates your blood and makes hematocrit readings look worse than they actually are. I drink 4-5 liters of water a day, more on training days. Half a teaspoon of sea salt in the first liter for electrolytes.
The Donation Mechanics
In Thailand I donate at the Thai Red Cross. Free, professional, takes about 45 minutes including the post-donation snack. They take 450 mL whole blood, which removes roughly 200 mg of iron and drops hematocrit by about 3 points.
In the US, you have options:
- American Red Cross — free, but they may turn you away if your hematocrit is over 54% on the day of donation (ironic). They also may not let you donate if you’re on TRT for performance reasons in some regions, depending on policies.
- Therapeutic phlebotomy — this is the medical version. Your doc writes a prescription for it (diagnosis usually “secondary erythrocytosis”). Most insurance covers it. You go to a hospital outpatient center.
- DIY phlebotomy — I do not recommend this and I won’t link to anyone who promotes it. Improperly done blood removal is dangerous.
If you’re being denied at the Red Cross, get a referral for therapeutic phlebotomy from any urologist or hematologist. They’ll write the order. Don’t skip donations because the bureaucracy is annoying.
What Lowers Hematocrit Without Donation
Things that help, in order of impact:
- Reduce TRT dose. Most direct lever. A 20-30% dose reduction will usually drop hematocrit 3-5 points over 8 weeks.
- Switch to daily micro-dosing. Smoother levels, less RBC stimulation per pulse.
- Switch from cypionate/enanthate to a shorter ester (propionate). Less drastic peaks. Adds injection frequency though.
- Increase aerobic training. Counterintuitively, endurance work increases plasma volume, which dilutes hematocrit. Going from zero cardio to 3x weekly Zone 2 will drop hematocrit measurably.
- Hydrate aggressively. Already covered.
- Add small amounts of cocoa flavanols or daily aspirin (low dose, doctor-supervised). Doesn’t lower hematocrit but reduces clot risk while you’re working on the underlying number. Not a replacement for actually fixing the hematocrit.
What Doesn’t Work
Things people will tell you to do that don’t really move the needle:
- Drinking more water alone (helps a couple points, not enough on its own at high hematocrit)
- Taking aspirin instead of donating (manages clot risk but doesn’t fix the underlying problem)
- Cutting carbs or doing keto (no meaningful effect on hematocrit)
- Switching brands of testosterone (no — the molecule is the same)
- “Estrogen control” through aggressive AI use (in fact, crashing estrogen worsens cardiovascular risk)
Real Talk on TRT Clinic Quality
This is the part of the article that’s going to ruffle feathers. A lot of TRT clinics — including some big online ones — do not test hematocrit aggressively enough. They check it once at intake and maybe once a year after that. They keep guys on 200 mg/week protocols that are absolutely going to push hematocrit into dangerous territory for many men. And they don’t follow up.
If your TRT provider:
- Doesn’t run a CBC every quarter
- Doesn’t have a stated hematocrit threshold for action
- Pushes back when you ask about reducing dose to manage RBCs
- Doesn’t discuss donation as standard practice
…then you need a better TRT provider. This isn’t optional knowledge for them — managing erythrocytosis is TRT 101.
My Current Numbers
For transparency, here’s where I’m sitting in early 2026:
- TRT dose: 30 mg testosterone cypionate, every other day (= 105 mg/week)
- Total testosterone: 950 ng/dL trough, ~1200 ng/dL peak
- Free testosterone: 220 pg/mL
- Hematocrit: 47% (post-donation, 8 weeks out)
- Hemoglobin: 15.8 g/dL
- RBC: 5.2
- Donation frequency: every 10 weeks
I’m essentially in the same place a high-T natural 25-year-old would be, hematocrit-wise. That’s the goal — supraphysiological androgens with eugammaglobulinic blood numbers.
The Bottom Line
Hematocrit management is the foundation of long-term TRT safety. It’s the number that separates guys who run TRT for 30 years and stay healthy from guys who get a stroke at 52. Test quarterly. Have action thresholds. Donate regularly. Split your dose. Hydrate. And get a TRT provider who takes this seriously.
None of this is hard. Most of it is free. The cost of ignoring it can be your life.
Related Articles
- My TRT Protocol after 10 years: What Actually Works and What’s Completely Overrated
- Complete Bloodwork Guide for TRT Patients: Essential Testing
- NAD+ and Rapamycin: The Longevity Stack I’ve Been Running For 2 Years
- The FDA’s War on Peptides Is a War on Your Right to Optimize Your Own Body
- Why I Live in Thailand: Performance Optimization, Freedom, and Building an empire from pattaya