SHBG (sex hormone binding globulin) is a protein which transports the sex hormones (testosterone, oestrogen and dihydrotestosterone (DHT)) in the blood. Hormones which are bound to SHBG are inactive which means that they are unavailable to your cells. Measuring the level of SHBG in your blood gives important information about your levels of free or unbound hormones which are biologically active and available for use.
What might a low result mean?
Low levels of SHBG usually correlates with higher levels of free or unbound sex hormones. Low SHBG can be seen in people who are obese, have an underactive thyroid, have polycystic ovaries (and therefore higher levels of free androgens) and those with adrenal dysfunction. It can also be caused by the use of anabolic steroids.
What might a high result mean?
High level of SHBG means that more of your sex hormones are bound to SHBG and are therefore unavailable to your cells. This means that you can have symptoms of low testosterone for example, even though your total testosterone level is normal. Causes of elevated SHBG include liver disease, an overactive thyroid, an eating disorder such as anorexia nervosa or steroid treatment. Sometimes if can demonstrate a hormone irregularity and can also increase during pregnancy.