Reply to thread

Yes, I am saying that almost all testosterone, exogenous or endogenous, must become free for it to be metabolized and/or excreted. There are some exceptions, such as when SHBG-bound testosterone binds to the megalin protein and is absorbed by cells. But the long half-life of SHBG suggests this activity is relatively small compared to the usual case of free T binding to androgen receptors.

The same principles apply to infrequent injections. In these cases steady state just means that each injection interval looks like the previous one. The only difference is that the rate of testosterone absorption declines more significantly over each interval, and this is reflected in free testosterone. This works because the rate of change in absorption is still slow compared to the half-life of testosterone in plasma.

Many factors influence subjective results. Some guys will be more sensitive to falling testosterone than others. Guys with low SHBG very likely do have problems with their levels of free estradiol compared to free testosterone. None of this suggests that absorption half-lives are very different.