I covered this in a recent video after my own hematocrit came back at 59. This is the long version: what each number actually measures, why the one everybody watches is the less informative of the two, and why the standard fix for the first quietly wrecks the second. WHAT HEMATOCRIT ACTUALLY IS Hematocrit is the percentage of your blood volume made up of red cells. It is a ratio, not a count. That single fact explains most of the confusion around it. A ratio can rise two completely different ways. You can add red cells, or you can remove plasma. Testosterone does the first. Dehydration, a hard training session, a sauna, a low-carb week, or a diuretic does the second. Both show up as a higher number on the same test, and the test cannot tell you which happened. So a man who trains in the morning, skips water, and gets drawn at noon can post a reading several points above his true resting value. He has not made a single extra red cell. He has concentrated the ones he already had. If you want a hematocrit number that means something, standardize the draw. Hydrated, not straight off a training session or a sauna, same time of day, same lab. One alarming reading taken under bad conditions is not a trend. WHY IT CLIMBS ON TESTOSTERONE The mechanism here is better understood than most people realize, and it is not just erythropoietin. Testosterone suppresses hepcidin, a peptide the liver makes to regulate iron. Hepcidin's job is to bind and degrade ferroportin, the channel that moves iron out of storage and across the gut into the blood. Less hepcidin means more ferroportin, which means more iron absorbed and more iron mobilized from stores. Testosterone opens the iron tap. This happens fast and it scales with dose. Serum hepcidin drops within about a week of starting, the suppression is dose-dependent, and it is more pronounced in older men. Hepcidin levels measured at four and eight weeks predicted how much hematocrit would eventually rise. Testosterone also raises erythropoietin and resets the relationship between erythropoietin and hemoglobin, so the body tolerates a higher red cell mass before it throttles production. Combine a reset set point with an open iron tap and you get reliable, dose-dependent erythrocytosis. It is the most common significant adverse effect of testosterone therapy, and it is not a sign something went wrong. It is the drug doing what it does.

I sat down with scientist David Kingsley to go through his actual blood work from his latest self experiment. His total testosterone increased from 749 to 960, while free testosterone also climbed significantly and SHBG barely changed. But the numbers are only part of it. We also talked about how he felt, energy in the gym, mood, sex drive, fertility markers, estradiol, IGF 1, and why tracking blood work matters when you experiment with your hormones. This is not a transformation based on somebody guessing how they feel. We actually have the before and after labs. Watch the full experiment: https://youtu.be/UDHRbra1r4k?si=cuvHYis9vq5BXA4N What result surprised you the most?

For anyone who has come off TRT, what have you found to be the best long-term protocol afterward? I’m coming off after 7 years . I understand nothing is going to fully replace TRT, so I’m not looking for the obvious “just stay on TRT” answer. I’m curious about combinations of things like HCG, enclomiphene, peptides, supplements, or anything else that people have actually used long term to get as close as reasonably possible to the benefits they had on TRT while maintaining natural testosterone production. What combination worked best for you, what doses/frequency did you use, how long have you stayed on it, and what did your labs look like compared with TRT? Also interested in libido, energy, mood, body composition, strength, and any side effects. Basically, if you were building the best sustainable post-TRT protocol possible, what would it look like?