Testosterone & Hormones
SHBG Explained: Why Total Testosterone Doesn't Tell the Whole Story
Sex hormone-binding globulin determines how much of your testosterone is biologically active. Here's what to know.
6 min read · XT Editorial Team · Reviewed & updated
What SHBG does
SHBG binds testosterone in the bloodstream, taking it out of circulation. Free testosterone — the unbound fraction — is what your tissues actually use.
What raises and lowers SHBG
Aging, alcohol, low-protein diets, hyperthyroidism, and some medications raise SHBG. Insulin resistance, obesity, and high androgen states lower it.
What to do
If total T looks fine but symptoms persist, ask for SHBG and free T. Magnesium, boron, and improved insulin sensitivity help nudge free T up by modulating SHBG.
Frequently asked questions
- Is high SHBG always bad?
- Not always — but it reduces free T. When symptoms align with low free T, lowering SHBG is the right target.
- Can supplements lower SHBG?
- Boron has modest evidence. The biggest levers are sleep, body composition, and protein intake.
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