How's your liver?

SHBG is created in liver, where globulin binds to the sex hormones.

Test total protein and albumin in blood work. Subtracting both will you a value for globulin. Various conditions can lead to albumin decrease, with subsequent globulin increase, which will increase the binding with sex hormones.

It is not an easy and straigth forward diagnosis. I would first look at liver, then thyroid, hepatites, HIV, diabetes, etc