What is Sex Hormone Binding Globulin and Why is it Important?
Hi, I’m Dr. Caplan from Helios Telemedicine for Men.
Our topic this week is, “Sex Hormone Binding Globulin and Why is it Important?”
When I started work on this video, I thought that it would be one of the easier ones. Wow, was I wrong. In the past, we knew that sex hormone binding globulin or SHBG was a protein made in the liver, increased with age, and that grabbed testosterone essentially permanently taking it out of circulation, but not a whole lot more. Recent research has shown that SHBG is a very important molecule with functions all by itself or in conjunction with testosterone and other sex hormones. So, SHBG DOES grab and hold onto testosterone so that the amount of free testosterone in the blood is reduced. That makes the measurement of the free or bioavailable testosterone levels important in our story. What we are learning is that SHBG has its own cell-surface receptors. We also know that, if it binds testosterone in the blood, it cannot bind to its receptor on the cell, but that if it binds to the cell, it can still bind testosterone. That means that there are possible different effects if the SHBG binds to a receptor and doesn’t then attract a testosterone vs. if it does. So SHBG can have an effect by itself or it can give testosterone a different way of effecting a cellular process. There is even a 4 th pathway for SHBG to function, but that one is even more complicated. The normal population-based range of SHBG is 10-57 nmol/L, but yours is likely to be much narrower.
Reduced SHBG Levels
SHBG may be reduced in patients with obesity, diabetes, hypothyroidism, kidney failure, and those on medications like cortisone and testosterone. If there is too little, we see increased risks for erectile dysfunction, insulin resistance and Type 2 diabetes, metabolic syndrome, non- alcoholic fatty liver disease, central fat gain, and all-cause mortality. There are no medications for intentionally raising of SHBG. It has been suggested that you could try increasing your ingestion of caffeine, limiting protein intake or trying a supplement with cadmium. I’m not making any guarantees here and would advise moderation.
Elevated SHBG Levels
SHBG levels may be elevated in hyperthyroidism, elevated FSH, chronic inflammatory diseases, Infections like Hepatitis C and HIV, insulin resistance and diabetes, elevated estradiol, alcohol and caffeine abuse, cigarette smoking, and medications like estrogen receptor inhibitors, anticonvulsants, and metformin, maintaining a vegan diet, or ingesting too much cadmium. If there is too much, we there can be hypertension, bone loss and increased fracture risk, increased bad cholesterol and cholesterol stones resulting in gallbladder surgery, and degenerative joint disease leading to joint pain and surgery.
Lowering SHBG Levels
The SHBG levels may be lowered by weight loss, reduction in caffeine and alcohol intake, reduction in simple carbohydrate intake, increased protein intake, increased intake of cruciferous vegetables like broccoli, cauliflower, Brussels sprouts, kale, bok choy, cabbage, and radishes. You can also try various supplemental vitamins, minerals, and herbs such as boron, zinc, magnesium, Vitamin D, fish oil, ashwagandha, tongkat ali, fenugreek, and stinging nettle extract as these may directly or indirectly effect SHBG levels. Medications like Anastrozole or DIM reduce estradiol also reducing SHBG.
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