T Nation

HPTA Basics and the Effects of AAS On It


Let me start off by saying that I am not a medical professional, just someone who likes to research information and become as knowledgable as possible. This thread is meant to start and further discussion on the basics of how our bodies produce natural Test, estrogen, LH, FSH, etc., and how it all relates in the use of AAS. By all mans if I am incorrect in something please correct me as this is meant to be educational and not to spread misinformation. Lastly I will say that The information in here Ii feel is not so easy to find and wanted to collect it all in one place, so that any newbie can understand how their body works a little bit before deciding to alter it with hormones and possibly ruin their bodies’ natural balance.


  • E2 = Estradiol
  • T = Testosterone
    -HPTA = Hypothalamic-Pituitary-Testicular-Axis (can also be HPG
    -LH = Luteinizing Hormone
    -FSH = Follicle Stimulating Hormone
    -GnRH = Gonadotropin-Releasing Hormone
    -DHT = DihydroTestosterone
  • HCG = Human Chorionic Gonadotropin
  • ER = Estrogen receptor

Here we go: The way male bodies naturally produce test begins in the Hypothalamus, which is where your body secretes GnRH. This signal is sent to the anterior pituitary gland, which when it receives the GnRH, in turn releases the appropriate amounts of LH and FSH. FSH plays a role in spermatogenesis (sperm production) and LH stimulates the Leydig cells within the testes to produce T. This T then binds to several receptors within the body, and also converts to both DHT where it exhibits androgenic effects, and E2 through aromatase. As more T is produced it reaches a point where your body then send s signal to stop GnRH secretion and thus testosterone production and spermatogenesis. This is known as the negative feedback loop. Your body fluctuates like this approximately 6 times a day.

That is how your body maintains homeostasis. Now we can get into the use of AAS (I will give a very basic cycle as an example). When you read about the HPTA being shut down or whatever on the forum, it is in reference to how all (or some) of these systems are no longer working properly ( which often happens when you listen to your boy at the gym who tells you Adex is optional and you should do 500 mg of tren and 1g of test for your first cycle because why not and that PCT is for pussies).

Lets say your cycle looks something like this:

200 mg Test E/ E3D
.5 mg Adex EOD

We won’t get into PCT since there is plenty on this forum about that, though I will touch on one thing quickly namely how Clomid and Nolva actually work within the body: Clomid binds to oestrogen receptors with the hypothalamus, which then causes a release of FSH and LH from the pituitary, which is why it is used in PCT. Nolva has a similar effect and also competes with estrogen in breast tissue to bind to the ER, thus it is very effective for treating gyno.

With the introduction of exogenous T into your body several things happen. First your Hypothalamus receives the signal that hey look at all this T! Your body will start to aromatase like mad to keep your levels normal. Your body will realise there is too much conversion and realise I need to slow down production. So no more GnRH. Thus no FSH or LH production. This is when you go into “shutdown”. This is where HCG can come in handy. HCG is treated by your body as if it were LH. So your body will keep up its own natural production of test, your balls won’t shrink, not as much at least, and recovery will be easier. Thats why HCG is highly recommended on cycle, but not necessarily “required”. Touching back on aromatase and higher conversion rates due to the exogenous T, this is where Adex comes in and is “required” while on cycle. Adex slows down conversion of test to E2 thus preventing your levels from being crazy out of whack when you go off cycle. It will also help prevent gyno symptoms. You must however be careful not to over do it, as you don’t want to crash your E2, cause you will feel like ass.

That is a basic overview of how shit goes down. I hope this helps at least one person in understanding their own bodies and what effects all of these medications have on them.