SHBG and PCOS: what TikTok gets right and wrong

What did @polybiotics actually say?

The creator explained that SHBG is a blood protein that binds testosterone and estrogen, making those hormones inactive. They then made two specific claims worth examining: first, that PCOS "could be due to a deficiency" in SHBG, and second, that exercise and the combined oral contraceptive pill are among "the best ways" to raise SHBG levels. The pill framing was notable because they acknowledged upfront that many people with PCOS dislike it.

The explanation of how SHBG works is basically correct. When SHBG binds to androgens like testosterone, those bound hormones can't easily dock with androgen receptors, so they can't drive symptoms like acne or hair thinning. That part is solid biochemistry. The more contested territory is what SHBG's role actually is in PCOS causation versus being a downstream marker of something else entirely.

Does the science back this up?

Partially, yes. Low SHBG is consistently documented in women with PCOS, but whether that's a cause or a consequence is genuinely unsettled. The creator hedged appropriately with "could be due to," which is the right level of confidence given the evidence.

Multiple studies have confirmed that women with PCOS have significantly lower SHBG than controls. Lim et al. (2012, Human Reproduction) found SHBG was inversely associated with androgen excess and insulin resistance in PCOS cohorts. The problem is that insulin resistance, which is present in roughly 70% of PCOS cases, directly suppresses hepatic SHBG production. So the low SHBG might be a symptom of insulin dysregulation rather than an independent driver. A genome-wide association study by Chen et al. (2011, American Journal of Human Genetics) did identify SHBG gene variants linked to PCOS risk, which supports a more causal role, but it is far from settled science. The creator's cautious phrasing was warranted.

On exercise raising SHBG: yes, there is decent evidence. Zhu et al. (2019, Journal of Clinical Endocrinology and Metabolism) found aerobic exercise increased SHBG in women with PCOS over a 16-week intervention. The combined pill raising SHBG is also well-documented. Ethinyl estradiol in combined OCs stimulates hepatic SHBG synthesis, sometimes tripling circulating levels.

What did they get wrong (or right)?

They got the mechanism broadly right. Where the video oversimplifies is in framing low SHBG as a potential root cause of PCOS rather than being clear it's more likely a feature of the condition, driven heavily by insulin resistance and androgen excess rather than sitting upstream of them.

The claim that inactive hormones "can't cause problems like acne and hair thinning" is accurate but incomplete. Free androgen index, which accounts for both total testosterone and SHBG, is clinically more useful than either alone. Some women with PCOS have normal total testosterone but low SHBG, which is exactly why SHBG measurement matters in clinical workup. That context would have strengthened the video considerably.

The pill recommendation is defensible for symptom management but deserves more nuance. Combined OCs raise SHBG and lower free androgens, which does help symptoms. However, they also mask the underlying hormonal pattern, which makes diagnosis and monitoring harder. For someone newly suspected of having PCOS, starting the pill before proper workup is a real clinical concern, though the creator wasn't explicitly telling anyone to start it.

What should you actually know?

If you have PCOS and you're wondering about SHBG, here's what actually matters for your care. SHBG is a useful biomarker, not a standalone diagnosis. A low SHBG with normal total testosterone can still mean meaningfully elevated free testosterone, which your provider should calculate using the free androgen index.

Insulin sensitization through lifestyle changes, and in some cases metformin, raises SHBG indirectly by reducing the insulin-driven suppression of hepatic production. Barber et al. (2006, Journal of Clinical Endocrinology and Metabolism) showed metformin increased SHBG in PCOS patients alongside improvements in insulin sensitivity. Exercise raising SHBG is real, but the effect size matters: resistance and aerobic training both help, with more consistent effects seen in longer interventions of at least 12 weeks.

The combined pill raising SHBG is real. But it also suppresses LH and FSH, which means if you stop it and your symptoms return, you haven't treated anything, you've borrowed time. Any conversation about the pill for PCOS should include what your goals are: symptom relief, contraception, or fertility planning, because the right answer differs.

• Get both total testosterone and SHBG measured, not just one.
• Calculate free androgen index: (total testosterone / SHBG) x 100.
• Ask your provider whether insulin resistance is contributing before assuming SHBG is the primary issue.
• Exercise interventions of 12 or more weeks show the most consistent SHBG improvements in PCOS research.