There are basically two very important reasons why we need to care about estradiol.
The first is that estradiol is a powerful testosterone receptor antagonist. What this means to us men is that estradiol creates a very strong bond to the androgen receptors of testosterone and renders them useless.
However, when testosterone binds to an androgen receptor, it activates that receptor and we get the physiological effects we’re all looking for. Now, when estradiol binds to that same receptor it blocks testosterone from binding, yet it does not activate the receptor, so in short nothing happens.
This means that if your estradiol serum level is high, no matter how much exogenous testosterone you take it isn’t going to help you as it should because too many of your androgen receptors are now blocked by estradiol and your free testosterone has nowhere to go.
Exogenous testosterone can’t do you any good if it doesn’t have receptors available to activate…simple enough.
Now, things can get worse believe it or not… newer research is showing that elevated levels of estradiol can cause the down regulation of androgen receptors. What this potentially means is that your body may respond to higher levels of estradiol by creating fewer androgen receptors as cells are replaced in a normal regeneration cycle.
So, not only does estradiol block the available androgen receptors as noted, it may cause your body to produce fewer of them in the future!
This is where many physicians get it wrong ;and is one primary reason why just raising testosterone serum levels alone as a mono-therapy may not provide any immediate or long-term benefits. It may be that the receptors have been down regulated; so there will be a need to lower estradiol levels and increase testosterone levels in order to get a man’s body to up-regulate again and this could take some time.
The second reason we care about estradiol in men is that we also have estrogen receptors and estradiol will bind to them and cause them to activate. This is fine if you want to grow man boobs (gynecomastia), suffer from erectile dysfunction, add belly fat and get an enlarged prostate, among other things; but not so good if you want to look and feel like a healthy man.
Keep in mind, the aromatase enzyme lives in the skin and has a propensity for abdominal fat; meaning the more belly fat you have the higher level of aromatase you will have. If you have excessive abdominal fat, chances are that your testosterone is low and estrogen is high. Not good.
Where Estrogen Comes From
Let’s forget environmental and dietary estrogens for now. The primary pathway for estradiol production is via the conversion of testosterone to estradiol by the aromatase enzyme.
What this means is that the aromatase enzyme found in every man’s body binds to testosterone and chemically synthesizes it to estradiol (E2).
Think about this for a minute and realize that this conversion is a double edged sword. All in one process you’re 1) losing testosterone and 2) gaining estradiol.
Obviously this is not a healthy state to be in and one that needs to be managed correctly.
This is where aromatase inhibitors (AI), like anastrozole, come into a well planned testosterone replacement therapy protocol. An AI will bind to the aromatase enzyme and prevent it from converting your testosterone to estradiol.
Keep in mind, and many practitioners get this wrong, that AI’s do not work directly on estradiol nor on the estrogen receptors. It is SERM’s like Clomid and Nolvadex that bond to estrogen receptors.
SERM’s and AI’s are different compounds, so don’t get them confused. Clomid, an AI, acts as an estrogen antagonist and will not stop the aromatization process. It disrupts the estrogen receptor bond formation process.
So, an AI gives us that double edged sword; but now in reverse. An AI will prevent the loss of testosterone to conversion and thus lowers our estradiol levels; which helps keep our androgen receptors available for testosterone.
Keep in mind that anastrozole is a powerful aromatase inhibitor (antagonist) and that too much can easily cause you to push your E2 level too low. Its half life is 46.8 hrs so this needs to be kept in mind upon initiating a dosing schedule. In most all cases it is suggested to start with the lowest possible dose and titrate up based on frequent blood work, until stable levels are attained.
Less is more here! Both high and low estradiol come with similar side effects such as joint pain, loss of libido, erectile dysfunction and moodiness.
Estradiol Follows Testosterone
Here’s where many doctors and other medical practitioners get it wrong; they forget that estradiol follows testosterone. As your testosterone serum levels elevate, so will your estradiol levels.
If your doctor is not doing something to manage your estradiol levels (like taking an AI) then you likely aren’t going to get anywhere with higher testosterone serum levels because your higher estradiol levels are just going to cancel out any beneficial effect from the testosterone. Your exogenous testosterone can’t do you any good if all your androgen receptors are all bound up with estradiol.
For those of us with “age related” or “obesity related” low testosterone levels, this is a serious issue because our bodies are already converting testosterone to estrogen at a fast rate due to the excessive aromatase activity; remember aromatase activity is significantly elevated in the obese and also the elderly.
If you’re a younger, leaner man with low testosterone levels for other reasons, aromatization may not be as much of an issue, but trust me…it still matters. Keep in mind that many fifty plus year old men have higher estrogen levels than women the same age. As we age, we become more like women both physically and emotionally.
Excessive body fat produces estrogen and aromatase enzymes. If you’re carrying extra body fat, one of the best things you can do to help your hormone balance is to lose that fat. Central obesity will not only wreak havoc on your hormonal profile, it will also lead to an earlier demise and just as importantly, a poor quality of life. High cholesterol, insulin resistance, high blood pressure, metabolic syndrome, cardiovascular disease, increased risk for stroke, erectile dysfunction and even depression are all strongly linked to central obesity. It is no consequence that low testosterone is linked to all of the same problems. It’s that vicious cycle mentioned earlier; low testosterone -> more belly fat -> lower testosterone -> even more belly fat and so forth. Losing that belly fat is one of the best things you can possibly do for your health and well-being.
Problems Associated With Low Estradiol
Some well-meaning but overzealous physicians have the mindset that lower is better, which is the wrong type of mindset. In fact, sustaining low levels of estradiol for lengthy periods of time can be downright detrimental!
Here are just some of the issues associated with having your estradiol level too low:
• A feeling of being lethargic, sluggishness, and fatigued
• Dry skin and hair
• Erectile dysfunction
• Loss of libido
• Sore, achy joints
• Inability to concentrate
• Potential risks for osteoporosis and bone fractures
• Potential cardiovascular and immune risks
“In Range” Does Not Mean “Normal”
One of the biggest and more frustrating problems you’re likely to face is the problem of most traditionally trained Doctors believing that any blood test value that is “in range” is “normal” and therefore “fine”.
Reference ranges comprise 95% of the population. In order to be out of range you need to be either in the bottom 2.5 percentile or top 2.5 percentile. Think about that for a moment. If you were to go to your primary care physician and show him your testosterone level of 300, he would most likely tell you you’re within range and therefore don’t need testosterone therapy. Fact is, you are in the bottom 3 percentile. Are you okay with that? Do you think the doctor, who refused to treat you based on your “normal” lab result, would be satisfied if his own testosterone level were in the bottom 3 percentile? Of course not. Yet, too many of those doctors refuse too many patients the treatment that can literally change their lives due to “normal” lab results. It’s extremely unfortunate.
So, while low testosterone might be “normal” from a lab reference range perspective that doesn’t mean it’s good, healthy or normal.