Total testosterone isn't the whole story: what labs actually show

What did @nancyychristine actually say?

The creator argues that a high total testosterone reading on labs shouldn't automatically trigger panic or a dose reduction. Her core claim: "It's not your total testosterone that matters. It's about how much of it is free and active in your body." She explains that SHBG binds testosterone and renders it unavailable to tissues, so free testosterone is the more meaningful number. She also ties side effects like hair loss specifically to DHT conversion, which she says depends on available testosterone, not total. She shares a personal anecdote: her total testosterone hit 300 and she almost cut back unnecessarily because free testosterone wasn't being tested.

This is a reasonably coherent explanation of a real physiological concept, delivered to an audience that is likely undertreated and undereducated about testosterone therapy. Credit where it's due: she's pointing women toward a real gap in standard lab monitoring.

Does the science back this up?

Mostly, yes. The distinction between total and free testosterone is not fringe thinking. It's well-supported in endocrinology literature, and the limitations of total testosterone as a standalone marker are documented.

SHBG binds testosterone tightly, and only the unbound fraction, roughly 1-3% of total testosterone in women, is immediately bioavailable to tissues. Rosner et al. (2007, Journal of Clinical Endocrinology and Metabolism) raised significant concerns about the accuracy of free testosterone assays, but the conceptual framework of SHBG reducing bioavailability is not disputed. Davison and Davis (2003, Journal of Clinical Endocrinology and Metabolism) found that free testosterone levels better correlated with androgen-related symptoms in women than total testosterone did.

On the DHT point, she's broadly correct. Hair follicle sensitivity to dihydrotestosterone, produced via 5-alpha reductase from free testosterone, is the established mechanism behind androgen-related alopecia. Trueb (2002, Dermatology) confirmed that local DHT activity at follicles, not serum total testosterone alone, drives androgenic hair loss in genetically predisposed individuals.

What did they get wrong (or right)?

She gets the concept right, but oversimplifies in ways that could mislead. Saying "it's not your total testosterone that matters" is too absolute. Total testosterone is not meaningless. It's a practical screening tool, and many clinicians use calculated free testosterone derived from total testosterone and SHBG together, precisely because direct free testosterone assays are notoriously unreliable in women. The Endocrine Society's 2010 guidelines specifically flagged that commercially available free testosterone tests have poor accuracy at the low concentrations typical in women.

Her claim that high total testosterone with normal free testosterone means "your risk of side effects is actually much lower" is plausible but not fully validated in prospective trial data for menopausal women on TRT. She presents it with more certainty than the evidence warrants.

The personal anecdote about a total testosterone of 300 is relatable, but "300" without units or context is clinically incomplete. 300 ng/dL in a postmenopausal woman is substantially elevated compared to typical female ranges of 15-70 ng/dL, and dismissing that without knowing the free testosterone and clinical picture is a reasonable concern, not just panic.

What should you actually know?

Free testosterone and SHBG testing genuinely do add meaningful clinical information that total testosterone alone misses, especially in women on TRT where SHBG levels can be affected by oral estrogen use. This is a real and underappreciated issue in how women's hormone labs are often run.

That said, free testosterone measurement in women is technically difficult. Equilibrium dialysis is the gold-standard method, but it's not widely available in commercial labs. Most standard panels use analog immunoassay methods that are known to be inaccurate at low female concentrations. Rosner et al. (2007, JCEM) specifically recommended against using these assays in women. Calculated free testosterone using the Vermeulen formula from total testosterone, SHBG, and albumin is often more reliable than a direct free T result from a standard lab panel.

The bottom line: she's right that total testosterone alone doesn't tell the full story. But the solution isn't simply "also test free testosterone" if your lab is using an inaccurate assay. Ask your provider specifically whether they're using calculated free testosterone or equilibrium dialysis, and whether they're interpreting results within female-specific reference ranges.