> For the complete documentation index, see [llms.txt](https://docs.beoptimal.ca/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.beoptimal.ca/biomarker-panels/male-performance-panel/sex-hormone-binding-globulin.md).

# Sex-Hormone Binding Globulin

**Sex hormone-binding globulin (SHBG)** is a protein produced mainly in the liver that binds to sex hormones in the blood, controlling their activity. High SHBG levels mean more hormones are bound and less are available for use, potentially leading to symptoms of low testosterone in men and high testosterone in women. Low SHBG levels indicate fewer hormones are bound, allowing more to be active. SHBG plays a crucial role in regulating hormone levels, affecting health outcomes like muscle mass, bone density, and fertility.