How testosterone actually works.
Testosterone is the primary androgen in men. It governs muscle, bone, mood, libido, cognition, and metabolic function. When it declines, those systems decline with it. The science is clear; the treatment is well-established. The only question is whether it's right for you.
The decline is real, and it starts earlier than most men think.
By most clinical measurements, total testosterone in men begins to decline around age 30, falling roughly 1% per year. Free testosterone — the biologically active fraction — often declines faster, because sex hormone-binding globulin (SHBG) tends to rise with age, binding more of the available testosterone.
By 45, the average man has free testosterone levels significantly below where he was at 25. By 55, the difference is dramatic. The symptoms — fatigue, brain fog, loss of drive, body composition shifts, mood changes — are not aging. They're hormone shifts that aging makes more pronounced.
What "low" actually means.
Reference ranges from major labs cover an enormous span — Quest's lower bound for total testosterone in adult men is around 264 ng/dL, while the upper bound is over 900. A man at 280 is technically "in range," but a 35-year-old at that level is functionally hypogonadal compared to where he should be.
The clinical question isn't "are you in range?" — it's "where in the range are you, given your age, your symptoms, and your goals?" Most men we see test in the lower third of the range and present with multiple symptoms. That's the population testosterone replacement therapy was designed for.
How TRT works.
Testosterone replacement therapy is exactly what it sounds like: prescribing exogenous testosterone to bring serum levels back into a healthy, optimized range. The most common form is testosterone cypionate, an injectable ester with a half-life of roughly 8 days, typically administered weekly or twice-weekly.
Within 4–6 weeks of starting therapy at an appropriate dose, most men report meaningful subjective improvement in energy, mood, and libido. Body composition changes follow over 3–6 months. Lab markers stabilize and can be used to fine-tune the protocol.
What we monitor.
TRT is medicine, not a supplement. It has effects beyond raising testosterone, and managing those effects is the job of a physician who knows what they're looking at. We monitor:
- Total and free testosterone — to confirm the protocol is delivering the intended dose
- Sensitive estradiol — testosterone aromatizes to estrogen; left unmanaged, this drives water retention, gynecomastia, and mood issues
- Hematocrit — TRT can elevate red blood cell count; we monitor and intervene before it becomes a clinical problem
- PSA — prostate-specific antigen, baseline and ongoing
- Lipid panel and metabolic markers — for cardiovascular health
If any marker drifts, your physician adjusts the protocol. This is normal, expected, and the entire reason real medical oversight matters.
What TRT is not.
TRT is not a workaround for poor sleep, bad diet, or chronic stress — those issues will limit any results you see. It is not a performance-enhancement scheme; we treat clinical hypogonadism, not "how do I get jacked." It is not a one-size-fits-all protocol; doses and adjuncts vary widely based on individual labs and response.
And it is not appropriate for everyone. Men with active prostate cancer, untreated severe sleep apnea, certain cardiovascular conditions, or fertility goals should consider alternatives. Your physician will tell you if you're not a candidate. We'd rather lose a customer than treat the wrong one.
The evidence base.
The Endocrine Society's clinical practice guidelines on testosterone therapy in adult men with hypogonadism, the TRAVERSE trial published in NEJM in 2023, and the Testosterone Trials all support the safety and efficacy of properly monitored TRT in men with clinical or laboratory evidence of low testosterone. The science is settled enough that the standard of care is widely accepted; what's not settled is access — which is what we built ANVIL to address.
"The medicine is the same whether you walk into a clinic in Beverly Hills or get it shipped to your door. The friction shouldn't be."