Anastrozole Research Study
Anastrozole is what is known as an Estrogen-Blocker. Estrogen-Blockers are used to inhibit the production of Estrogen by the body and to prevent the conversion of Testosterone into Estrogen via biological mechanisms inside the body. For post-menopausal women, Anastrozole is commonly prescribed as part of breast cancer treatments, because the presence of Estrogen exacerbates breast cancer. The brand name form of Anastrozole, Arimadex, is produced and distributed by the pharmaceutical giant, AstraZenaca.
Among men, Anastrozole Therapy is commonly prescribed along with Testosterone Therapy in order to inhibit the body's natural propensity to convert excess Testosterone into Estrogen, especially among obese patients and patients taking forms of Testosterone Therapy prone to inducing spikes in Testosterone Production.
Also, bodybuilders, athletes, and weight-lifters commonly take Anastrozole in combination with high levels of Testosterone in order to abuse the Anabolic effects of Testosterone while mitigating the side-effects related to excess Estrogen and Testosterone, including Gynecomastia.
Anastrozole Clinical Study
In one particular study, published in 2009, researchers studied the impact of Anastrozole Treatment upon the production of Testosterone and other sex hormones among men. They also measured a number of other co-varying factors, including cholesterol levels, PSA Counts, Strength, and Body Composition. All patients in the study were individuals suffering from Low-T, and all patients were treated with Anastrozole Estrogen-Blocker for twelve months.
After a year of treatment, researchers found that the men experienced an increase in Testosterone of around fifty percent, and this increase was sufficient to put men right in the middle of a healthy, adult Testosterone Range. This was coupled with an average twenty percent decrease in Estradiol levels, although the average Estradiol levels were normal on average.
Anastrozole had a number of beneficial effects. The Estrogen-Blocking Treatment increased concentrations of Luteinizing Hormone, Dihydrotestosterone and Free Testosterone (also known as Bioavailable Testosterone). These effects were significant when compared to the placebo group.
Unfortunately, the increase in Androgen Production and decrease in Estradiol production did not lead to significantly enhanced strength or body composition, but it also did not have a negative impact on cholesterol balance, prostate health, and PSA Levels.
Andropause and Male Health - Testosterone and Estrogen
It has long been known that the male aging process is strongly correlated with a steady and constant drop in the production of male androgens such as Testosterone and Dihydrotestosterone. It is also known that Estrogen Production also drops at the same time as these male Androgens decline, albeit at a slower rate.
This transformation eventually leads to a condition known as Testosterone Deficiency, Andropause, or simply Low-T. At the same time, Estradiol ratios increase in relation to Testosterone Concentration as a result of their differing rates of decline. This is because, although there is less Testosterone, the body converts that Testosterone into Estradiol at a faster rate with age.
Researchers are still attempting to discover the full implications of this biological change, and how it effects male health. Hormone Scientists are also attempting to figure out exactly how this biological change occurs, as the mechanisms are not yet fully understood.
Why Do Testosterone Levels Drop Faster than Estrogen Levels in Men?
Endocrinologists do have some hypotheses however. Here are some of them:
Reduced production of Testosterone as a result of increased Estrogen synthesis.
Decrease in the mass of Leydig Cells, which are responsible for the production of Testosterone.
Leydig Cells may become increasingly insensitive to stimulation from the Pituitary, which could inhibit Testosterone Production.
As men grow older, they could be producing less Testosterone as a result of increased activity of Gonadostatin Hormones or other hormones which suppress the production of Testosterone as a factor of age.
How Does Anastrozole Increase Testosterone Levels?
Aromatase Inhibitors such as Anastrozole and Arimadex are able to enhance Testosterone production because they reduce the production of Estradiol. The presence of excess Estradiol produces a negative feedback mechanism which encourages the enhanced release of Gonadotropin-Releasing Hormone, Luteinizing Hormone, and Follicle Stimulating Hormone by the Hypothalamus (GRH) and the Pituitary (LH and FSH). All of this acts together in a way which stimulates the testes and adrenal glands to produce more Testosterone.
Why is Anastrozole Useful for Testosterone Replacement?
There are a number of reasons why it would be highly beneficial to use Anastrozole as a means to improve Testosterone Production, if it were effective:
Anastrozole is effective in pill form, making it very easy to take with minimal inconvenience.
It can mitigate the side-effect of Gynecomastia related to Testosterone Therapy
Protects the cardiovascular system and the cognitive faculties from the negative effects of excess estrogen.
Anastrozole may be beneficial in lieu of Testosterone Therapy as a means to enhance Testosterone Production without the risk of Benign Prostatic Hyperplasia (as of yet unfounded)
Previous Research: Hypogonadism and Anastrozole
One of the inspirations that lead researchers to conduct this study regarding the impact of Anastrozole on Estrogen and Androgen Levels was another study which evaluated the effects of Anastrozole upon 37 geriatric patients suffering from hypogonadism. This study produced some very similar results with regard to how Anastrozole improved Testosterone Concentrations as well as normalized the ratio between Testosterone and Estradiol.
The original study was conducted over the course of three months, as opposed to the year-long study conducted in 2009. These results were corroborated in another study, although that study did not involve a control-placebo group.
The Testes May Lose Their Ability to Produce Testosterone as Men Grow Older
Because this study was over the course of a year, rather than only three months, it provided greater information with regard to how the human body responds to long-term treatment with Anastrozole. In this study, for example, results after three months were nearly identical to those in the other earlier three month studies, but then over the course of the next nine months, androgen concentrations dropped.
The researchers hypothesize that the decrease in Testosterone Concentration could be the result of increased resistance to the Estrogen-Blocking Medication. Researchers found that, although Testosterone Production dropped over the course of the last nine months, Luteinizing Hormone Levels remained at high levels. This suggests that although the Hypothalamus and Pituitary are sending sufficient signals to produce youthful levels of Testosterone, that the Leydig Cells in the testes, for unclear reasons, are no longer capable to meet the demands of the body.
It has been observed however, that Leydig Cells are less responsive to Luteinizing Hormone when there is a higher concentration of ligands. Because of the stable Estradiol Concentrations over the course of the nine months, as well as well-kept medication diaries and monitored pill-counts, the researchers are able to discount noncompliance as a contributing factor to reduced Testosterone Concentrations.
Effects of Anastrozole on Body Composition Differ from the Effects of Testosterone Therapy
The vast majority of studies on why men with Low-T Hypogonadism have been treated with Testosterone have shown that Andropause Therapy reduces body fat and increases muscle mass. Many studies also show that Testosterone Restoration has a positive impact on physical strength.
In this particular study, the same benefits do not appear to be apparent with regard to Anastrozole. After a year of medication with Anastrozole, there were no significant changes in muscle mass, strength, or body composition observed. These results are similar to those of other studies which utilized Estrogen-Blockers for a shorter period of time.
Why Is Anastrozole Alone Not as Effective as Testosterone Treatment?
It could be that the patients did not have Low-T of sufficient severity to produce positive biological changes in body composition. The researchers don't feel that this is the case, however, because there have been other studies in which men with the same degree of Low-T were able to experience significant gains in body composition directly from therapy.
A second potential explanation for this lack of change in fat and muscle mass is that Anastrozole alone, or at the dose administered, does not have the capability to produce the increase in Testosterone necessary to lead to significant gains with regard to body composition. Most studies which have led to increased Muscle Mass and Decreased Body Fat were the result of increasing Free Testosterone Levels to High-Normal, whereas this treatment only raised Testosterone Levels to Mid-Normal.
Another issue with Anastrozole Pills is that they, alone, don't produce the same increases as Bio-Identical Testosterone Formulations, because these treatments bypass the digestive system and deliver the dose directly to the blood stream. Testosterone Administered via Injection, Patch, or Cream, produce Testosterone Peaks which are higher than average.
Since this study only produced peak Testosterone Levels that were mid-normal, and concentrations dropped over the course of the year of therapy, this may have been the reason why Free Concentration did not produce significant Body Composition gains.
It is also possible that the reduced concentrations of Estradiol resulting from Anastrozole Treatment could have inhibited the gains that one would normally expect from treatment. In animal subjects, there is evidence that male mice increase body fat if aromatase genes are not activated. This is also true if Estrogen Receptor-α is not activated. Among rats that have been castrated, the administration of Estrogen actually protects against weight gain and has the ability to generate muscle mass.
In relationship to this animal study, men that have experienced Prostate Cancer are more resistant to weight gain when treated with an Androgen Blocker which increases Estradiol Levels known as Bicalutamide. These benefits were enhanced in relationship to Gonadotropin-Releasing Hormone, which simultaneously inhibits Estrogen and Androgen Production. Interestingly enough, it appears that Estradiol does play a particular role in protecting healthy body composition among male patients.
Anastrozole Does Not Impact the Prostate Gland
All signs from this study show that Anastrozole and Arimadex have no impact upon the health of the prostate. In particular, Anastrozole does not lead to prostate enlargement, and it does not lead to increased PSA Counts. Researchers hypothesize that since Anastrozole decreased Estradiol Levels while increasing Testosterone Levels, it counteracted the effect upon the prostate that is often the result of Testosterone Therapy used alone.
The scientists that produced this study took the time to place special emphasis upon this connection between the Prostate and Estrogen. It may be that Testosterone Therapy combined with Anastrozole may have the ability to provide the normal benefits of Testosterone Restoration and Optimization while protecting the prostate from risk of the potential side-effect of Prostate Enlargement.
There is further biological evidence that this may be the case. Estradiol Levels are positively correlated with increased incidence and severity of Benign Prostatic Hyperplasia, and the body also becomes more sensitive to Aromatase as men grow older. Animal studies have also shown that Estrogen Injections enhance Prostate-Specific Antigen, and they also lead directly to the proliferation of stromal cells and prostatic epithelial cells which are associated with Benign Prostatic Hyperplasia. Animal studies have also shown that drugs which inhibit Estradiol actually have the ability to alleviate the effects of the condition.
Anastrozole Does Not Alter Cholesterol Balance or Increase Red Blood Cell Count
In this study, there is no evidence that Anastrozole Treatment negatively impacts cholesterol or causes polycythemia. Today, researchers are highly interested in figuring out how to provide Testosterone Therapy to patients with Low-T while preserving or enhancing cardiovascular health and cholesterol levels. Many studies clearly point out that healthy Testosterone Levels are associated with improved heart health and enhanced cholesterol balance.
Other studies regarding Testosterone Therapy, on the other hand, show that some forms of Testosterone Treatment can sometimes lead to negative consequences in regard to cholesterol. There is also evidence that oral Estrogens reduce LDL cholesterol levels and increase HDL cholesterol levels in both sexes. Estrogens administered via cream have a limited impact on cholesterol.
These positive changes in cholesterol associated with Estrogen pills do not seem to provide heart benefits. This provides even more evidence that Cardiovascular Risks are complex, and there are a number of factors which control heart health, not just cholesterol. Other issues that can affect Cardiovascular Health include endothelial function, coagulation, insulin resistance, and inflammation.
Anastrozole Study Limitations
There is one powerful issue which can impact the results of this study. There is no clearly delineated definition of what is considered Low-T among older men. Because there is no agreed-upon definition, it makes establishing clinical guidelines for Andropause and Low-T a difficult thing to do.
This study used a more common definition of Age-Related Low-T to choose its subjects, but other researchers have tighter guidelines for what patients are considered Andropause Sufferers. If the researchers would have used tighter guidelines for Testosterone Deficiency, they may have found positive effects upon muscle mass and body fat, but they argue that, had they used these more stringent guidelines, the study could not effectively be compared to the majority of other Low-T Studies.
Anastrozole Study Summary
To summarize the above study and its effects, researchers found that one year of Anastrozole Pill Treatment had the ability to suppress Estradiol Levels and enhance Testosterone Production among adult males over the age of sixty struggling with mild or moderate Low-T.
This treatment was able to restore Testosterone Concentrations associated with that of young and healthy males, but it did not have a positive impact upon strength and body composition. This outcome could have been the effect of inhibited Estradiol Production in relationship to increased Testosterone Levels, or it could have been the result of a developed resistance to the Estrogen-Blockers.
Future studies could monitor the effects of Anastrozole (Arimadex) Estrogen-Blockers upon other issues associated with Low-T, including reduced sexual function, quality of life, cognitive health, insulin sensitivity, and bone mineral density. Such studies would enhance our knowledge of how Estrodiol and other Estrogens impact the health of men, and how Estrogen interacts with Testosterone and Testosterone Restoration.
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