Dr. Betty Murray explains why SHBG, a liver-produced protein that binds testosterone and estradiol, is the most overlooked hormone test in perimenopause. In that stage, SHBG below 40 ng/dL signals high androgen activity even when testosterone reads normal. Insulin resistance, obesity, and oral estradiol suppress it; transdermal estradiol and thyroid optimization raise it.
Now, SHBG is probably the most under-ordered test, particularly in PMOS. It's produced by the liver and it binds to testosterone and estrogen, keeping it inactive. Insulin suppresses SHBG, and especially in a woman, estrogen— estradiol stimulates SHBG. So depending on where you are on in the perimenopausal journey, you may not see this while you're looking at labs. If we're trying to assume what's really happening, the optimal ranges are about 70 to 130. If we have PMOS, we want a SHBG under 40, because that'll significantly drive androgen activity even with low or normal T, right? Low or normal testosterone. What drives it down is insulin resistance, obesity, hypothyroidism. That almost always is a problem. And then oral estradiol. If you're doing any kind of oral estradiol, this will make it worse. And then what drives it up or improves it's transdermal estradiol, right? So topical forms of estradiol for perimenopause and menopause, thyroid optimization, insulin sensitivity improvement.
