Should SHBG always be tested alongside testosterone levels?

What did @drkatiebrussard actually say?

The claim is straightforward: high sex hormone binding globulin (SHBG) can make someone with normal total testosterone blood levels feel symptomatic of low testosterone. She extends the same logic to estrogen. Her bottom line is that SHBG should always be tested alongside hormones. That is a defensible clinical position, and it is worth unpacking exactly how much the evidence supports it.

She says high SHBG can make someone "feel like they are low testosterone" even when total testosterone reads normal. This is the core of the video, and it is not a fringe idea. It is the conceptual basis for why free testosterone measurements exist in the first place. The question worth asking is whether the relationship between SHBG, free testosterone, and symptoms is as clean as a short TikTok makes it sound.

Does the science back this up?

Mostly, yes. SHBG binds testosterone tightly, and only the unbound fraction, roughly 2-3% of total testosterone in most men, is considered biologically active at the tissue level. When SHBG rises, a larger share of circulating testosterone gets bound, leaving less free testosterone available. This is not controversial.

Ruokonen et al. (2008, European Journal of Endocrinology) demonstrated that free testosterone calculated from total testosterone and SHBG correlates more closely with clinical symptoms of androgen deficiency than total testosterone alone. Similarly, Vermeulen et al. (1999, Journal of Clinical Endocrinology and Metabolism) validated the calculated free testosterone formula that most labs use today, specifically because total testosterone was insufficient on its own. The Endocrine Society's clinical practice guidelines acknowledge SHBG variability as a reason total testosterone can be misleading in certain populations, including obese patients, older men, and those with thyroid disorders. So the basic premise holds up.

What did they get wrong (or right)?

She got the core mechanism right. Where the video is incomplete rather than wrong is the symptom piece. Saying high SHBG can make someone "feel like" they have low testosterone implies a fairly direct line from SHBG to subjective symptoms. That line is messier than it sounds.

Symptom-based diagnosis of androgen deficiency is notoriously unreliable. Bhasin et al. (2010, Journal of Clinical Endocrinology and Metabolism) found that low libido, fatigue, and mood changes, the classic low-testosterone symptoms, have poor specificity and overlap substantially with depression, sleep disorders, and other conditions. A patient with high SHBG and normal total testosterone might have low free testosterone on paper and still feel fine. Another might feel terrible despite numbers that look adequate. The video skips over this complexity entirely.

The estrogen point is also underdeveloped. SHBG does bind estradiol, though with lower affinity than testosterone. The clinical implications for estrogen-related symptoms in women are less well-characterized than the testosterone literature, and lumping them together without qualification is a bit of an oversimplification.

What should you actually know?

Testing SHBG alongside total testosterone is genuinely useful, and she is right to recommend it. But knowing your SHBG number is a starting point, not an answer. Here is what that context looks like in practice.

• Free testosterone can be measured directly (equilibrium dialysis is the gold standard) or calculated using total testosterone and SHBG. Calculated free testosterone is widely used but has known limitations, particularly at extremes of SHBG.
• Conditions that raise SHBG include hyperthyroidism, liver disease, aging, and certain medications including anticonvulsants. Conditions that lower it include obesity, insulin resistance, hypothyroidism, and anabolic steroid use. Context matters enormously.
• The Endocrine Society recommends confirming low testosterone with at least two morning measurements of total testosterone before acting on any result, with SHBG as supplementary information, not a standalone diagnostic tool.
• Symptoms should drive clinical decision-making alongside labs, not in spite of them. A number alone, whether SHBG or free testosterone, does not tell a clinician how a patient is doing.

Ordering SHBG is cheap and genuinely informative. The video's recommendation is sound. The framing just gives a slightly too-tidy picture of how hormone symptoms actually work.