Serum sex hormone binding globulin (SHBG) is a sex hormone bound to the protein globulin. It is a protein secreted by the liver that binds to sex hormones such as testosterone and dihydro-testosterone in men and estradiol in women, a type of estrogen which is the main sex hormone in women. When the globulin protein decreases in the body as a result of one of the reasons we will mention, this leads to an increase in the percentage of free testosterone in the body. On the contrary, when the protein globulin increases in the body, it binds to free testosterone (active hormones) a strong bond that is difficult for the body to break, which leads to a decrease The percentage of free testosterone in the body. Causes of low SHBG in the body Hypothyroidism, a condition in which your body does not make enough thyroid hormones. Type 2 diabetes mellitus. Excessive use of steroid medication. Cushing's syndrome, a condition in which your body makes too much of a hormone called cortisol. For men,