SHBG and hormones: what 'normal' labs actually mean

What did @nprinciotti actually say?

The creator argues that SHBG, which she calls your "sex hormone binding gluten" (she means globulin), acts like a "taxi cab" that picks up testosterone, estrogen, and DHT and renders them biologically inactive. Her core claim: even if your labs look normal, high SHBG can leave you symptomatic, showing up as hair thinning, low libido, fatigue, dry skin, and irregular cycles. She points to hormonal birth control, thyroid issues, poor liver function, blood sugar instability, and low protein intake as SHBG drivers. She closes by suggesting viewers get a "functional lens" read on their panels through her bio link.

The framing is broadly reasonable. The mechanism she describes is real. But several specific claims are either oversimplified, partially wrong, or missing important context, and one repeated mispronunciation is worth flagging because it signals the kind of loose terminology that can erode trust in otherwise solid information.

Does the science back this up?

Mostly yes, with real caveats. SHBG is a glycoprotein produced primarily in the liver, and it does bind testosterone, DHT, and estradiol with varying affinity. Only unbound, or "free," hormone is considered biologically active at the tissue level. This is not fringe functional medicine, it is standard endocrinology.

A 2010 review by Rosner et al. in the Journal of Clinical Endocrinology and Metabolism confirmed that total testosterone measurements can be misleading when SHBG is abnormal, and that free or bioavailable testosterone provides better clinical correlation in some populations. Similarly, research by Wallace et al. (2013, Clinical Biochemistry) supports SHBG as a clinically relevant marker for metabolic and hormonal health. The link between hormonal contraceptives and elevated SHBG is also well-documented. Panzer et al. (2006, Journal of Sexual Medicine) found that oral contraceptives significantly raise SHBG, sometimes persistently after discontinuation. The liver-SHBG connection is real too. Liver disease affects SHBG synthesis, though the direction of change depends on the type and severity of dysfunction.

What did they get wrong, or right?

She gets the core mechanism right. SHBG binds sex hormones and reduces their free fraction. That part holds up. The symptom list she associates with high SHBG is also clinically plausible, though it is worth noting these symptoms are non-specific and can have dozens of causes unrelated to SHBG.

Where she gets shaky: "a high T4" driving SHBG is an oversimplification. Hyperthyroidism broadly, not just elevated T4, is associated with increased SHBG (Sumer et al., 2013, Journal of Thyroid Research). Attributing it to T4 specifically misreads the mechanism. Her claim about "estrogen dominance" as an SHBG driver is also problematic. Estrogen actually tends to increase SHBG production, not the reverse, which means estrogen dominance would more likely raise SHBG, not be caused by it. The causal arrow she implies is backwards. And repeatedly calling it "sex hormone binding gluten" across the whole video is not a one-time slip. It undermines credibility on a topic where precision matters. To her credit, the birth control and protein intake claims are well-supported.

What should you actually know?

SHBG is a legitimate clinical marker that many standard panels do not include by default, and the creator is right that its absence can leave gaps in interpretation. If you are symptomatic despite normal total hormone levels, asking your provider about free testosterone or free estradiol, alongside SHBG, is a reasonable clinical question. This is not fringe thinking.

That said, interpreting SHBG in isolation is problematic. Reference ranges vary by lab, age, and sex. A single high SHBG result does not confirm hormone deficiency, it is one data point. The symptom cluster she lists, fatigue, hair loss, weight gain, low libido, is so broad that it overlaps with thyroid disease, iron deficiency, sleep disorders, depression, and dozens of other conditions. High SHBG should prompt a conversation with a licensed clinician, not a self-directed "hormone reset." If you are being evaluated for TRT or hormone therapy, a provider reviewing free and total hormone levels together with SHBG gives a much fuller picture than total levels alone.