How much testosterone is converted to estradiol?

I've seen a few numbers thrown around. From "0.2%" to "0.3%", now does that mean a fraction of a percent or does it mean 1/3rd of all test is converted to E2?

Management of Estradiol in Men- What Do Studies Show? | Discounted Labs

Conversion of blood androgens to estrogens in normal adult men and women

What confuses me is they write it like "0.39%" but then use "4.5%" in other contexts.

Maybe Dr saya could clear this up or it could just be a misunderstanding of math on my part.

So either this is a dumb question or it's a question no one can answer.

According to my latest labs https://www.excelmale.com/forum/showthread.php?8533-My-New-LabCorp-Labs my E2 is 32 / my total T is 1183 = .027 or 2.7%

This is highly different person to person.

Vince said:

According to my latest labs https://www.excelmale.com/forum/showthread.php?8533-My-New-LabCorp-Labs my E2 is 32 / my total T is 1183 = .027 or 2.7%

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32 pg/ml = 3.2 ng/dl. 2.7% of 1183 ng/dl testosterone = 32 ng/dl of E2 which is 320 pg/ml.

So it can't be a whole percent, pure math alone shows it's not the case. This also assumes that excretion and metabolism of test and E2 is the same, if E2 is excreted or metabolized faster or slower than test, total levels of both is impossible to use to measure production rate. It could be that estradiol bioaccumulates in the body, thus less testosterone is broken down in order to maintain serum levels of E2.

It also assumes that the molecular mass of E2 and test are the same I think. Basically I think it implies that 1 testosterone -> 1 estradiol. That is not the case, testosterone has a higher molar mass than E2 does, so it's more like 2 testosterone -> 1 estradiol. Keep in mind, this is not the correct ratio based on molar mass, and is based on my limited understanding of chemistry.

The reason I am asking this is because I want to know how much testosterone is consumed to make estradiol, as in THEORETICALLY how much would an amount of AI enough to prevent ANY testosterone from being converted to E2 increase testosterone levels?

trt4me said:

This is highly different person to person.

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Of course it is, but I am not asking on an individual basis.

I am asking for understanding purposes. It doesn't pertain to a certain individual.

johndoesmith said:

http://www.discountedlabs.com/blog/management-of-estradiol-in-men-what-do-studies-show/

and the transfer constant, [ρ]BBTE2, for testosterone conversion to estradiol is 0.39% in males and 0.15% in female
​

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC297476/
What confuses me is they write it like "0.39%" but then use "4.5%" in other contexts.

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Just looking at the paper you reference the 4.5% mentioned is for the conversion of androstenedione to testosterone. But the data for this paper was collected after infusing androstenedione and testosterone so I would assume that most of the T didn't have time to be bound to SHBG during the time of the test, which only lasted 150 minutes. So the 0.39% may more accurately be applied to free testosterone levels, don't know for sure.

HarryCat said:

Just looking at the paper you reference the 4.5% mentioned is for the conversion of androstenedione to testosterone. But the data for this paper was collected after infusing androstenedione and testosterone so I would assume that most of the T didn't have time to be bound to SHBG during the time of the test, which only lasted 150 minutes. So the 0.39% may more accurately be applied to free testosterone levels, don't know for sure.

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Yes. You're right, but that's not what I was asking. This is more of a math related question in a sense, I was confused by their useage of percentage than their methods.

The reason I pointed out "4.5%" is that they then use "0.39%". Why use whole numbers as percentages then use decimals? If I am remembering math class correctly, then "0.39%" is equivalent to "39%". Or basically 39/100ths.

Ultimately I want to know whether it is approximately 1/3rd of all testosterone converted to estradiol, or a fraction of 1%.

0.39% is 0.39/100 or 0.0039, so you would take the testosterone number and multiply by 0.0039 to get the estrogen number. Likewise with 4.5% you would multiply the starting quantity by 0.045.

Nelson Vergel said:

4.5 % is for total androgens to total estrogens NOT from testosterone to estradiol.

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I think the 4.5% is actually for the conversion of androstenedione to testosterone. From the full text of the referenced paper:

HarryCat said:

0.39% is 0.39/100 or 0.0039, so you would take the testosterone number and multiply by 0.0039 to get the estrogen number. Likewise with 4.5% you would multiply the starting quantity by 0.045.

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There you go! That's the answer I was looking for. It was a misunderstanding of math on my part.

So basically it's a fraction of 1%.

4.5 % is for total androgens to total estrogens NOT from testosterone to estradiol.

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Nelson, thank you for that. I did understand that the 4.5% referred to something else, if you read what I said carefully, I was confused by the "4.5%" due to the expression of percentages. It had nothing to do with what the actual hormones were, more to do with their use of numbers I didn't understand.

johndoesmith said:

So either this is a dumb question or it's a question no one can answer.

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Or... it's a Sunday ;-)

Just poking fun at ya Johndoesmith!

Seems Nelson beat me to it and answered your question sufficiently.

The amount of E2 in the system compared to the amount of T is truly minuscule.

As an illustration of this, take a look at this previous "food for thought" post I made which illustrates that even FEMALES typically have MORE TESTOSTERONE than estradiol in their system:

https://www.excelmale.com/forum/sho...ht-Testosterone-and-Estrogen-in-Males-Females

Dr Justin Saya said:

Or... it's a Sunday ;-)

Just poking fun at ya Johndoesmith!

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Haha yeah I realized that could come off a bit impatient. Re-reading my posts I apologize if I came off a bit harsh to anyone.

Actually my question was how much testosterone is consumed by the aromatization process? If a guy on TRT with 1000ng/dl total test was given enough AI to shut down ALL aromatase, how much would his test increase?

No offense towards nelson, but he answered a question I never really asked.

johndoesmith said:

Haha yeah I realized that could come off a bit impatient. Re-reading my posts I apologize if I came off a bit harsh to anyone.

Actually my question was how much testosterone is consumed by the aromatization process? If a guy on TRT with 1000ng/dl total test was given enough AI to shut down ALL aromatase, how much would his test increase?

No offense towards nelson, but he answered a question I never really asked.

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Not much at all.

Let's say for a hypothetical patient that their testosterone is 1000ng/dL and their estradiol is 40 pg/mL. For that hypothetical patient, even if you COMPLETELY shut down the estradiol (to 0 pg/mL), since there is a 10:1 conversion of pg/mL to ng/dL -> this 40pg/mL of estradiol would only mathematically equate to "saving" 4.0 ng/dL of testosterone.

In my opinion, the much larger CLINICAL impact of changes in estradiol levels is on FREE TESTOSTERONE (vs total testosterone) levels by way of impacting SHBG.

Dr Justin Saya said:

Not much at all.

Let's say for a hypothetical patient that their testosterone is 1000ng/dL and their estradiol is 40 pg/mL. For that hypothetical patient, even if you COMPLETELY shut down the estradiol (to 0 pg/mL), since there is a 10:1 conversion of pg/mL to ng/dL -> this 40pg/mL of estradiol would only mathematically equate to "saving" 4.0 ng/dL of testosterone.

In my opinion, the much larger CLINICAL impact of changes in estradiol levels is on FREE TESTOSTERONE (vs total testosterone) levels by way of impacting SHBG.

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Haha good. It's hard to convey tone and inflection with text only :\

I'm asking more for pure knowledge and understanding, not really attempting to make a change myself! Wouldn't only free testosterone be available for aromatization?

I also assume that since estradiol is excreted on a constant basis(as is testosterone and other hormones) that this is a continual process, so MORE than 4ng/dl of test is consumed to replace the excreted estradiol, right?

johndoesmith said:

Haha good. It's hard to convey tone and inflection with text only :\

I'm asking more for pure knowledge and understanding, not really attempting to make a change myself! Wouldn't only free testosterone be available for aromatization?

I also assume that since estradiol is excreted on a constant basis(as is testosterone and other hormones) that this is a continual process, so MORE than 4ng/dl of test is consumed to replace the excreted estradiol, right?

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Very astute questions and observations. I haven't discussed or taught aromatization in that much detail outside of training other TRT physicians, so kudos to you johndoesmith.

Based on what I have learned, you are correct that only free testosterone should be available for use and conversion by the aromatase enzyme (not T bound by SHBG...however "loosely" bound T with albumin creates some complexity in this evaluation as it can be unbound...so there are some shades of grey here).

As I was discussing with a physician I recently trained, this creates an interesting comparison of free T and estradiol as BOTH are in concentrations that are typically reported in pg/mL. I've been observing these relationships (of free testosterone and estradiol both measured in pg/mL) for quite some time and have been trying to glean some clinically useful info to put into practical use with patient management. This is a work in progress detecting patterns, but there are so many moving variables that pattern recognition is not very starighforward.

To your second question - yes both T and E are constantly being excreted (and replaced).

Dr Justin Saya said:

Very astute questions and observations. I haven't discussed or taught aromatization in that much detail outside of training other TRT physicians, so kudos to you johndoesmith.

Based on what I have learned, you are correct that only free testosterone should be available for use and conversion by the aromatase enzyme (not T bound by SHBG...however "loosely" bound T with albumin creates some complexity in this evaluation as it can be unbound...so there are some shades of grey here).

As I was discussing with a physician I recently trained, this creates an interesting comparison of free T and estradiol as BOTH are in concentrations that are typically reported in pg/mL. I've been observing these relationships (of free testosterone and estradiol both measured in pg/mL) for quite some time and have been trying to glean some clinically useful info to put into practical use with patient management. This is a work in progress detecting patterns, but there are so many moving variables that pattern recognition is not very starighforward.

To your second question - yes both T and E are constantly being excreted (and replaced).

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Ha, thank you. I enjoy researching this topic, most of my questions are lost as thoughts or questions come to me when I'm driving and I ALWAYS tell myself "I'll remember that for later!" and it never happens.

I do recall discussing with you the possibility of Test bound to SHBG unbinding, therefore could aromatize. I imagine that is probably something no one honestly knows at this point in time.

I digress, I have noticed a bit of a pattern myself with my free test and E2 readings, E2 is always about 2-3pg/ml higher than my free test. They follow very closely.

I imagine that individual aromatization rate is what you're trying to determine with FT/E2 observations and symptom relief. Taking into consideration that only FT is aromatized, FT/E2 ratio is significantly lower than TT/E2 ratios, which points to a HIGHER amount of free test than total test aromatized. Which explains (partially if you disregard SHBG increasing when E2 increases)why FT increases when E2 decreases as less is "used", plus COULD partially explain the clinical impact of E2 level changes.

What kind of info have you discovered from FT/E2 patterns?

Yes, I agree, this is incredibly complicated, it's like playing whack a mole but with hormones.

Still monitoring for trends. Overall so far notice E2 does tend to "follow" (in magnitude of changes) free T more so than changes in total T. This appears to be another potential reason why low SHBG tends to create more complexity (more sensitivity) with E2 levels. Low SHBG -> more free T -> more E2 conversion AND...more FREE E2 as the kicker.

There is a T dose related increase in estradiol that eventually plateaus. The increase is higher in older men.

Effect of testosterone dose and age on estradiol and DHT conversion.

How to Predict Estradiol and DHT at Different Testosterone Doses

I was able to come up with a table using the predictive model equation derived from data in this study: The Effects of Injected Testosterone Dose and Age on the Conversion of Testosterone to Estradiol and Dihydrotestosterone in Young and Older Men Summary This video discusses a research paper...

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