Hematocrit creeping up on TRT, anyone else tracking this alongside HRV?

Question

Been on testosterone cypionate for about 7 months now, roughly 140mg split into two shots per week. Started tracking bloodwork every 6 weeks because i wanted to catch any drift early. Hematocrit was 46% baseline, crept up to 51% by month 4, then 53% at month 6. Ngl that got my attention pretty fast. The thing i noticed alongside it was my resting HR dropped about 4 bpm but HRV actually went down too, not up. Which seems counterintuitive? You'd think lower resting HR means better recovery. But thicker blood probably changes cardiovascular dynamics in ways that mess with autonomic balance? Or that's my guess anyway, could be something else entirely. I started donating blood which brought hematocrit back to 47% and HRV ticked up within about 10 days. Seemed like a real connection but it's just my own experience, not exactly a controlled experiment. Curious if anyone else here has tracked hematocrit and HRV at the same time on /peptides/testosterone-cypionate? Keen to hear whether the HRV dip pattern matches what you saw. Also wondering if people who split dose more frequently like EOD see less hematocrit drift or if it's more about total weekly mg than injection frequency?

student748 · Accepted Answer

For what it is worth i've been tracking hrv heaps for training and one thing that stands out to me is that hrv is super sensitive to blood viscosity changes, even small ones. Like when i was training at altitude my hrv tanked for the first week even though my resting hr dropped, and the mechanism is probably similar to what you're describing. Thicker blood = more afterload on the heart = sympathetic nervous system working harder even at rest. So your guess seems pretty sound to me. The EOD dosing question is interesting, i'd be keen to hear from anyone who's tried it too. My understanding is hematocrit rise is more driven by total exposure over time than peak levels, so splitting more frequently might not help much, but i'm genuinely not sure. Have you looked at whether your ferritin crashed after donating? That can mess with hrv too in the other direction.

greg_codes · Answer

Yeah the altitude comparison is a really good call actually, never thought about it that way but the mechanism lines up pretty well. More afterload driving sympathetic tone even at rest makes sense of why HR went down but HRV didn't follow. Ngl the fact that your HRV recovered after acclimatising is interesting too, makes me wonder if there's an adaptation window for the TRT hematocrit thing as well? Or if it just keeps climbing and you have to stay on top of donations. Keen to hear if anyone's gone EOD and seen a flatter hematocrit curve.

sleep_coastal · Answer

That altitude comparison is a really good parallel. Anecdotally I saw the same HRV dip when my hematocrit hit 52-ish, and it bounced back after a donation. The afterload explanation makes sense to me too. What I wonder is whether the HRV drop shows up before the hematocrit number looks alarming, like an early warning signal worth watching.

greg_codes · Answer

Yeah nah that's exactly what got me thinking about it. Looking back at my data, HRV started dipping around month 3 when hematocrit was maybe 49-50%, before i'd have flagged it as a problem. Resting HR was still dropping so it looked like a positive trend on paper. The HRV going the wrong direction was the thing that didn't fit. Could've been a decent early signal if i'd trusted it sooner instead of waiting for the bloodwork to confirm. Ngl i'll be watching HRV trend more closely next time around.

Hematocrit creeping up on TRT, anyone else tracking this alongside HRV?

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