This write up should answer most of the questions that we get related to the topic, and will give you a basic understanding on the importance of timing PCT properly and how it all works.
Some of the most serious long-term side effects that many users of anabolic steroid users worry about are hypogonadism, which is a condition where one’s testes no longer produce sufficient testosterone, and infertility. In almost all cases sufficient time off between cycles along with the correct use of ancilliaries like HCG, clomid and nolvadex can prevent these problems.
Most informed steroid users follow Post Cycle Therapy protocols to help recover natural testosterone production as soon as possible after a steroid cycle. But if timed incorrectly or not done properly PCT can fail, resulting in slow HPTA recovery and the loss of most new muscle gained on the steroid cycle.
Anabolic Steroids and the HPTA
Before we go into when to take what and what each PCT drug does, it is important to have a basic understanding of our body’s system that regulates testosterone and sperm production – The Hypothalamic Pituitary Testicular Axis (HPTA), and to see what happens to the HPTA when we take steroids.
The HPTA refers to the production of the hormones released by the hypothalamus, pituitary gland and the testicles that regulate a man’s sex hormones levels and spermatogenesis. Testosterone and sperm production begins when the Hypothalamus produces a hormone (GnRH) to stimulate the pituitary gland to secrete the hormone that instructs our testes to produce testosterone - Luteinizing Hormone (LH) and the hormone that initiates sperm production in our testes -Follicle Stimulating Hormone (FSH). When androgen or sex hormone levels are too high as they are when on a steroid cycle, they form a negative feedback loop which inhibits the hypothalamus’ production of GnRH, effectively shutting down the HPTA. LH and FSH levels then drop to near zero, which results in no natural testosterone production, testicular atrophy and a very low sperm count.
Testicular Shut Down and preventing it with HCG
Testosterone is synthesized and secreted by the leydig cells in the testes and when these cells are not functioning due to suppression from anabolic steroids they begin to atrophy. The longer the leydig cells are inactive, the more their receptors down-regulate, which means that post cycle our testes do not respond properly to the signal to produce testosterone. We then need to wait while our testes recover their ability to function normally, or we use HCG, which is an analog of LH and FSH to speed up the process by directly stimulating the leydig cells.
If you begin PCT with your clomid or nolvadex before your testes are back to normal function, your testes will not respond optimally to treatment and your PCT will not be very effective and could fail. So proper use of HCG and timing of PCT is essential. A
recent animal study
showed that exogenous testosterone enanthate given over 10 weeks increased the rate of leydig cell death and that after the 10 weeks the testes contained fewer leydig cells. So ideally we want to maintain testicular function on cycle by using HCG to continue our natural testosterone production. HCG
has also been proven
to maintain spermatogenesis in men on testosterone replacement therapy. So guys worried about fertility should without a doubt use HCG on cycle. 250IU twice a week is the recommended dose.
HCG is a hormone that we inject to directly stimulate the testes to produce testosterone. It is an analog of luteinizing hormone and therefore binds to LH’s target receptors exactly as if it were LH. Your testes can’t tell the difference between HCG and LH. It is also a weak analog of FSH but still strong enough to maintain healthy sperm production while taking exogenous testosterone. For optimal HPTA recovery post cycle it is best to use HCG on cycle to maintain endogenous testosterone production and prevent testicular atrophy. HCG is somewhat suppressive on the hypothalamic-pituitary part of the HPTA due to negative feedback caused by the testosterone production it stimulates. So only use it as part of PCT if you do not use it during your cycle because it will interfere with the efficacy of the Clomid and tamoxifen.
Hypothalamic and Pituitary Shut Down
Anabolic Steroids inhibit both GnRH and gonadotropin (LH & FSH) secretion. Long term suppression causes the cells that produce gonadotropins to downregulate and atrophy and they effectively stop working. Generally these gonadotrophs and the hypothalamus will recovery normal function within months of ending a steroid cycle,
but in some cases after long-term use spontaneous recovery does not happen
.
To treat hypothalamic-pituitary shut down effectively during PCT it is essential to only start taking clomid and tamoxifen when your circulating sex hormone levels have dropped to their normal range. All estrogens, androgens, progestins and anabolic steroids exert negative feedback on the hypothalamus and pituitary, preventing them from sending the chemical messengers to stimulate testosterone and sperm production. If you start treatment too early your hypothalamus will not respond and your PCT will be wasted. This unfortunately is very common and steroid users who do this repeatedly without sufficient time off between cycles are at a high risk of developing secondary hypogonadism. Responsible, informed cycling and PCT can prevent this.
How do Clomid and Tamoxifen/Nolvadex work?
Clomid and tamoxifen are both selective estrogen receptor modulators (SERMs) that we take to signal our brain to stimulate natural sex hormone production. This class of drugs binds to estrogen receptors on the hypothalamus and pituitary gland. The pituitary gland is fooled into thinking estrogen levels are lower than they actually are and it then secretes more LH, increasing testosterone production by the testes. Although clomid and tamoxifen seem very similar, clomid is a mixed agonist/antagonist while tamoxifen acts as only an antagonist, ie. anti estrogen. What this translates to is that clomid acts predominantly as an estrogen, rather than an anti estrogen, by sensitizing the pituitary to the action of GnRH. Tamoxifen is almost as effective as clomid in binding to estrogen receptors, but it has little to no ability to enhance the GnRH-stimulated release of LH. Tamoxifen is however a more effective anti estrogen. Clomid and tamoxifen do compete for receptors to bind to, so because of clomid’s unique estrogenic action on GnRH receptors it is advised to use it first before starting tamoxifen.
When to start PCT?
To calculate accurately when to start PCT we need to look at the type of AAS used, the doses and the duration of the cycle. Generally, using 3 to 4x the half-life of the longest acting steroid in our cycle is a safe estimate. But when using nandrolone and trenbolone which are very suppressive, or a very high dose cycle, it is best to wait a bit longer to be safe.
To put this in perspective, a healthy 30 year old man’s total testosterone level on average is around ±600ng/dL. After 12 weeks on a cycle of testosterone enanthate at 600mg/week it will be ±5000ng/dL. Using a half-life of 10 days would put him at 2500ng/dL 10 days after his last shot, 1250ng/dL after 20 days and 625ng/dL 30 days into his bridge to PCT. Now that his testosterone level has dropped to the normal range the negative feedback on the HPTA will be minimal and SERMs will be effective enough to start PCT.
Now if for example he had added tren enanthate to that cycle, after 30 days into his bridge his ‘normal’ 625ng/dL testosterone level combined with the remaining circulating trenbolone in his system would still be a very suppressive and SERMs would be ineffective. It would then be best to extend the bridge by about 2 weeks. Take this kind of scenario into consideration if you plan on stacking different injectables on your cycle.
It is also important to ensure that estradiol (predominant potent form of estrogen) is low when starting PCT. Estradiol is extremely suppressive on the HPTA, even more so than testosterone. By minimizing it we can stimulate our hypothalamus and pituitary much more during PCT, improving recovery, and boosting testosterone production. An AI like aromasin is advised, particularly if you have been using HCG through your bridge as HCG increases estradiol along with the testosterone it produces. Elevated estradiol will also cause libido problems if your T:E ratio gets too low so you might need to add in an a low dose of an AI just for this purpose, even if you do not get gyno symptoms.
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