Steroid hormones pathway

[robertin75]

Hi:

I have some questions regarding hormone pathways.

If someone has high estrone levels, does that mean that he will have high androstenedione levels, because it is one of the main precursors of estrone (via aromatization)?

Or, can someone have normal levels of androstenedione and very high levles of estrone? If that's the case, where can the high estrone can come from?

Also, if someone has low DHEA and normal or high-normal androstenedione, can we assume that 17 Hydroxyprogesterone is the main contributor for androstenedione production?

I guess that my main point is that if someone has a low value of a specific prohormone, should we assume that the hormone in which that specific hormone is catalized would also be low?

Sorry if this sounds complicated, but I'm trying to understand some hormone pathway things.

Thanks and any input is greatly appreciated,
Roberto

 

[SWALE]

Simple answer: no to all the above.

The levels of each individual (and there are many, many more than we see listed) hormone is determined as much by the activity of the enzymes involved as the precursors. This is the stuff of the "art" of the medicine.

 

[robertin75]

Ok, so how do you determine the activity of a specific enzyme since they cannto be measured directly?

Is this done by measuring the specific prohormone and the hormone in which a particular enzyme catalyzes it?

For example (and this may not be a real case), if someone has normal testosterone values, but very high Dihydrotestosterone values, can we assume that the enzyme 5-Alpha-reductase is overactive, since this is the enzyme that catalyzes T to DHT?

Also, I have another question , SWALE:

I was reading the following:

Aromatase has ten times higher affinity for androstenedione than testosterone. In the way of an analogy, the androstenedione-to-estrone pathway is a four-lane highway and the testosterone-to-estradiol pathway is a residential side street. I think this puts androstenedione at a distinct disadvantage compared to testosterone regarding potential estrogenic side effects.

Do you know if this means that slight increases in androstenedione will lead to high estrone levels, because of the high aromatase affinity discussed in the above paragraph?

Thanks for your help,
Roberto

 

[robertin75]

Bump, SWALE

 

[SWALE]

It is far too complicated--and expensive--to get into all that. Just not practical.

In the case of 5-AR, I look at the sex hormone levels and also the ratio of some adrenal hormones to get a feel for its activity level.