Steroid hormones are lipophilic and therefore must circulate bound to specific binding globulins, which ↑ their solubility.

In men, ↑ sex hormone-binding globulin (SHBG) lowers free testosterone → gynecomastia.In women, ↓ SHBG increases free testosterone → hirsutism.

OCPs, pregnancy → ↑ SHBG