SHBG Changes after Keto

[Gus80]

The myth that won't die. Changing SHBG in isolation does not affect free testosterone in normal situations, except transiently. It is total testosterone that responds to such changes. SHBG binds testosterone, so more SHBG means more total testosterone, not more free testosterone.

This is not what my unsuccessful experience of 7 years with TRT, performing exams every 3 months approximately, shows me.
Whenever my SHBG levels went down, estradiol and free testosterone went up a lot. The higher the dose of T, the greater the drop in shbg.

More SHBG = less free testosterone and less estradiol. ((men who respond well to higher doses of TRT).
Less SHBG = more free testosterone and more estradiol. (men who respond badly even to small doses of Testosterone, like me).

So much so that it is possible to increase free testosterone just by manipulating shbg with dht derivatives, even in the absence of extra exogenous testosterone.

But if you have any scientific article that says the opposite, I would like to read it.

 

[Systemlord]

More SHBG = less free testosterone and less estradiol. ((men who respond well to higher doses of TRT).
Less SHBG = more free testosterone and more estradiol. (men who respond badly even to small doses of Testosterone, like me).

So much so that it is possible to increase free testosterone just by manipulating shbg with dht derivatives, even in the absence of extra exogenous testosterone.

This seems to be a commonly held belief, however once your SHBG is fully saturated, Free T rebounds and therefore Free T can no longer be affected by SHBG. SHBG doesn’t affect testosterone production because there’s no mechanism for that, SHBG doesn’t increase or decrease testosterone production, not without changes in LH.

Also E-2 is weakly bound to SHBG, much less than Free T, and again once fully saturated, E-2 is no longer affected. If your have a guy with a Total T at 533 ng/dL, SHBG at 71 and he has low Free T, decreasing the SHBG in isolation will lead to a Total T value <300 and Free T remains unchanged.

So changes in SHBG doesn’t change Free T values. There are some medical conditions which raise the SHBG while also decreasing testosterone production, like starvation. So reducing SHBG isn’t going to do anything for your testosterone production.

 

[Cataceous]

...
But if you have any scientific article that says the opposite, I would like to read it.

Consider it a strong hypothesis, almost to the point of being a theory. @readalot points to support in the mechanistic literature, e.g. here.

I have also argued directly for it like this:

The working hypothesis is that in steady state conditions free testosterone is directly proportional to the production rate of endogenous testosterone, or to the dose rate of exogenous testosterone. Only two primary assumptions are necessary: 1) The rate of testosterone entering the system is matched by the rate of testosterone being metabolized and eliminated. 2) The rate of metabolism and elimination is proportional to the level of free testosterone, following the law of mass action. A secondary assumption is that the underlying rate constant for metabolic clearance is relatively static. There are situations in which this constant changes dramatically, presumably including damage to the liver. But we'd hope these would not be common.​

If the hypothesis is correct then it's clear that SHBG has little effect on free testosterone. ...​

In your case I'd first ask if you are using an accurate test for free testosterone? An immunoassay-based test is inaccurate and unusable. Calculated free testosterone can be viable if SHBG isn't extreme. What is the biological basis for your view? Is it tied to the notion that testosterone production or dosing drives total testosterone? This is probably incorrect unless you can find a flaw in the above reasoning.