Men, Do You Have Enough of This Female Hormone?

Dr. Frank Shallenberger, MD

October 31, 2022


As you may know, estradiol is a female hormone. In fact, it’s the most powerful of all the female hormones.

But men, even young men, make it. So there must be a reason for it.

That being the case, is it possible for a man to have a deficiency of estradiol? And if so, what kind of problems might he expect if he did?

These questions have been studied. And the answers may surprise you.

It wasn’t long ago that doctors didn’t pay much attention to estradiol in men. After all, it’s a female hormone. What possible importance could it be for a man?

And then we learned that excessive estradiol levels in men could cause some serious problems including blood clots, low libido, enlarged breasts, heart disease, strokes, depression, prostate enlargement, prostate cancer, and metabolic syndrome. So then the focus shifted to making sure that estradiol levels were low. But is there a point at which a low estradiol level in a man becomes too low?

Some men are born with a deficiency of the enzyme aromatase. Aromatase is the enzyme in men that catalyzes the production of estradiol. So these men have low to undetectable levels of estradiol. The most consistent problem that these men develop is abnormal bone growth and osteoporosis. They are also more likely to have cardiovascular disorders, infertility, and insulin resistance.

And here’s the clincher. When these men are given estradiol replacement therapy, these symptoms clear up. So it’s apparent that men need estradiol. It’s there for a reason.

A few years ago, some researchers wondered why men get osteoporosis. Osteoporosis is mostly a female problem, but men do get it. About 3-6% of men over the age of 50 will get osteoporosis. So what causes it? The researchers thought the most likely cause would be a decrease in testosterone, since testosterone increases bone mass. But they also knew that in women, estradiol was extremely important for maintaining bone health. So they set out to look at the relationship between these hormones and osteoporosis in men.

They studied 2,447 men aged 65 years and up. They measured their testosterone levels, estradiol levels, and bone density. They defined testosterone deficiency as having a blood level less than 200 ng/dl. They defined estradiol deficiency as having a blood level less than 10 pg/ml. And they defined osteoporosis as having a bone density score less than 2.5. Here’s what they found.

Of the men with normal testosterone levels, 6% of them had osteoporosis. Whereas, 12.3% of the men with deficient testosterone had osteoporosis. So testosterone deficiency is an obvious cause of osteoporosis in men. But when they looked at estradiol it got even more interesting.

Of the men with estradiol deficiency, 15.4% had osteoporosis. That’s more than the number of men that developed it from testosterone deficiency. And in the men who had a normal level of estradiol, only 2.8% of them had osteoporosis. That’s half as many men with normal testosterone and one-fourth as many men with testosterone deficiency. And for the statistically minded, all of these results were statistically significant.

So the results are clear. Even though testosterone is important at preventing osteoporosis in men, estradiol is much more important. So estradiol is essential for men. And at least when it comes to bone health, it is possible for a man to have too little estradiol. By the way, there are other studies that suggest that having a deficiency of estradiol may also increase the risk for cardiovascular disease. So men, the moral of this story is to keep an eye on your estradiol level.

First, make sure that your estradiol level doesn’t get too high. That means keeping it below 30 pg/ml. Lifestyle causes for elevated estradiol include too much alcohol, too much body fat, and lack of adequate exercise. The other cause for excessive estradiol is testosterone therapy. Some men will convert the testosterone they are getting into estradiol. So be careful if you have an estradiol level over 30 and you have any of these problems. If you do, work on them until you get your level down.

Second, in many men on testosterone therapy, the only way to keep a lid on the estradiol level is to take 0.5-1 mg of the medication anastrozole twice a week. The reason that testosterone therapy often results in higher levels of estradiol is because of the enzyme aromatase that I mentioned above. It converts testosterone into estradiol. Anastrozole is very effective at preventing the action of aromatase and thus preventing the estradiol level from getting too high. But sometimes it can work too well and create too low a level of estradiol. As you have seen, this may be every bit as bad as having too much estradiol. How low is too low?

In the study above, the low level the researchers chose was 10 pg/ml. That was definitely too low. But why not take young men as an example? Their estradiol levels rarely go below 15 pg/ml. So my advice is to make sure that your estradiol level does not go below 15.


Fink, H.A., S.K. Ewing, K.E. Ensrud, et al. “Association of testosterone and estradiol deficiency with osteoporosis and rapid bone loss in older men.” J Clin Endocrinol Metab. 2006 October;91(10):3908-15.

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