Sex Hormone Binding Globulin (SHBG) Levels
SHBG binds sex hormones and takes them out of circulation. High levels can mask what's really low bioavailable testosterone or estrogen, even when total levels look fine. This is the "hidden half" that standard hormone panels ignore.
What this measures
How your DNA shapes sex hormone binding globulin (SHBG) levels.
SHBG is the protein that binds sex hormones (testosterone, estrogen) in circulation — only the unbound (free) fraction is biologically active. The SHBG gene contains variants that shift baseline production. High SHBG ties up more testosterone and estrogen, reducing free hormone available to tissues; low SHBG leaves more free.
Carriers of SHBG rs1799941 and rs12150660 reduced-production variants are associated with lower SHBG levels — and proportionally more free testosterone and estrogen at the same total hormone levels. Carriers of higher-production variants are associated with the opposite pattern. The variant decides whether a "normal total testosterone" actually means normal free testosterone.
Insulin resistance lowers SHBG; weight loss raises it. Liver health affects SHBG production directly. Hormonal contraceptives raise SHBG meaningfully — sometimes enough to halve free testosterone, which explains some of the libido and energy changes reported on oral contraceptives. Thyroid status, alcohol, and certain medications all shift the picture.
A "normal total testosterone" report isn't the same conversation across SHBG variant patterns. Which SHBG variant you carry decides whether free hormone calculations (calculated free testosterone, bioavailable testosterone) matter in interpreting labs — and whether the right intervention is adjusting SHBG or adjusting total hormone production.
Sex Hormone Binding Globulin (SHBG) Levels is one specific finding in this system. Your Genomic Lifestyle Optimization Report shows where your variants place you on the hormones spectrum — and what you can do about it: it renders as a dark card with a color marker calibrated to your variants, opening with the gene mechanism and closing with a practical, mechanism-led recommendation.
Want to see what a real Mosaic dark card looks like? Walk through a sample report →
In context
Sex Hormones: the 6-insight cluster.
Sex Hormone Binding Globulin (SHBG) Levels is one finding in a tightly-related cluster. Mosaic sequences the other 5 alongside it so you see the whole biology — not an isolated data point.
Questions people ask
About Sex Hormone Binding Globulin (SHBG) Levels.
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