What did @onehottrail actually say?
The creator analyzed Doug Miller's latest blood work, which showed a total testosterone of 1340 ng/dL and free testosterone of 14.91 ng/dL. Their core argument: these numbers are achievable naturally, but only because of severely elevated SHBG, which they estimate at around 100 nmol/L. They also pointed out that "his free test is suboptimal when compared to his total," and that higher total testosterone with suppressed free testosterone is not actually a sign of optimal hormone health. The creator even shared their own labs to illustrate the point, reporting a total of 984 ng/dL but a free testosterone of 23.36 ng/dL.
The framing is clear: total testosterone is not the number that matters most. Free testosterone, the biologically active fraction, is what cells actually use. And in Miller's case, abnormally high SHBG is binding most of it up.
Does the science back this up?
On the core SHBG mechanics, yes, this is well-supported. SHBG binds tightly to testosterone, reducing the free fraction available to androgen receptors. When SHBG is elevated, total testosterone can look impressive on paper while free testosterone remains low or even deficient in functional terms.
The normal reference range for SHBG in adult men is roughly 10 to 57 nmol/L, depending on the lab and assay used (Handelsman, 2017, Journal of Clinical Endocrinology and Metabolism). An SHBG of 100 nmol/L would indeed sit well outside that range. High SHBG is associated with aging, liver disease, hyperthyroidism, caloric restriction, and high estrogen states, among other causes (Wallace et al., 2014, Clinical Endocrinology). The creator is correct that this mechanism explains how someone can have a very high total testosterone reading without the biological benefits typically associated with it.
The claim that free testosterone is measured in ng/dL at 14.91 deserves a small flag. Many labs report free testosterone in pg/mL rather than ng/dL, but the numbers cited are consistent with equilibrium dialysis methodology at the higher end of normal, so the units may simply reflect lab-specific reporting conventions rather than an error.
What did they get wrong (or right)?
They got the core biochemistry right. SHBG as a compensatory driver of high total testosterone is a legitimate and underappreciated concept in public hormone discourse. Most TikTok content about testosterone treats total T as the only number worth discussing, which is genuinely misleading, and the creator is right to push back on that.
The reference to "ARG expression" appears to be a shorthand for androgen receptor gene expression. That framing is loosely used here. Free testosterone availability does influence androgen receptor signaling, but receptor density, downstream transcription factors, and tissue sensitivity all complicate any simple correlation (Bhasin et al., 2018, New England Journal of Medicine). Saying free testosterone is the one marker that "really matters" is close to correct but slightly oversimplified.
The creator's back-of-envelope SHBG estimate of 100 nmol/L is a reasonable approximation, but it is an estimate. Without seeing Miller's actual SHBG number, presenting this figure with confidence risks overstating certainty. That said, the math is directionally sound.
What should you actually know?
If you are interpreting your own testosterone labs, total testosterone alone tells you almost nothing about functional androgen status. Free testosterone and SHBG should always be part of the panel.
SHBG is not a fixed number. It rises with age, caloric restriction, endurance training, and certain medical conditions. A man in his 20s who trains hard and eats a caloric deficit may have meaningfully higher SHBG than expected, which could suppress free testosterone even if his total looks normal or high. This is a real clinical scenario that goes undiagnosed when providers only check total T.
Reference ranges vary by lab and methodology. Equilibrium dialysis is considered the gold standard for free testosterone measurement, but many commercial labs use calculated free testosterone based on total T, SHBG, and albumin, which introduces additional variability (Morales et al., 2010, European Urology). Know which method your lab uses before drawing strong conclusions from the numbers.
Persistently elevated SHBG without a clear explanation warrants medical evaluation, not just optimization strategies. Liver function, thyroid status, and sex hormone-binding globulin genetics should all be considered before attempting to lower SHBG through lifestyle or supplementation.