Ovarian Syndrome is associated with insulin resistance and excess insulin lowers SHBG, which increases free testosterone levels. In the womb the human fetus has a low level of SHBG allowing increased activity of sex hormones. After birth, the SHBG level rises and remains at a high level throughout childhood. At puberty the SHBG level halves in girls and goes down to a quarter in boys. The change at puberty is triggered by growth hormone, and its pulsatility differs in boys and girls. In pregnant women in the third trimester of pregnancy the SHBG level escalates to five to ten times the usual level for a woman. A hypothesis is that this protects against the effect of hormone produced by the fetus. Obese girls are more likely to have an early menarche due to lower levels of SHBG. Anorexia or a lean physique in women leads to higher SHBG levels, which in turn can lead to amenorrhea. Type 2 diabetes Reduced levels of SHBG and also certain polymorphisms of the SHBG gene are implicated in the development of insulin resistance and type 2 diabetes. Such effects apparently involve direct action at the cellular level where it became apparent that cell membranes of certain tissues contain specific high-affinity SHBG receptors. Coagulation SHBG is a useful correlate and indirect marker of estrogen-induced procoagulation and by extension thrombosis, for instance with birth control pills. Medications Oral contraceptives containing ethinylestradiol can increase SHBG levels by 2- to 4-fold and decrease free testosterone concentrations by 40 to 80% in women. They can be used to treat symptoms of hyperandrogenism like acne and hirsutism. Some oral contraceptives, namely those containing high doses of ethinylestradiol (which have been discontinued and are no longer marketed), can increase SHBG levels by as much as 5- to 10-fold. Some medications, such as certain anabolic steroids like mesterolone and danazol and certain progestins like levonorgestrel and norethisterone, have high affinity for SHBG and can bind to it and displace endogenous steroids from it, thereby increasing free concentrations of these endogenous steroids. It has been estimated that therapeutic levels of danazol, methyltestosterone, fluoxymesterone, levonorgestrel, and norethisterone would respectively occupy or displace from testosterone 83–97%, 48–69%, 42–64%, 16–47%, and 4–39% of SHBG binding sites, while others with low affinity for SHBG such as ethinylestradiol, cyproterone acetate, and medroxyprogesterone acetate would occupy or displace from testosterone 1% or fewer SHBG binding sites. Endogenous steroids Measurement