TRT Clinics Are Selling You Hormonal Chaos

The testosterone-to-estrogen-to-IGF-1 chain is one of the most misunderstood systems in men's health, and most of the men paying the most money to manage it understand it the least.

Start with the big picture. Your body makes testosterone, and some of that testosterone gets converted into estrogen by an enzyme called aromatase, which is the enzyme responsible for turning androgens into estrogens throughout your tissues. That estrogen then travels to your liver and signals it to produce something called IGF-1, which stands for insulin-like growth factor 1 and is the downstream molecule responsible for most of the tissue-building, recovery, and body composition benefits people associate with growth hormone. Growth hormone does not do much of that work directly. It sends the signal, and IGF-1 does the building.

That is the whole chain: testosterone converts to estrogen, estrogen tells the liver to make IGF-1, IGF-1 does the work.

Now here is where the TRT clinic model starts to fall apart.

When a man goes on testosterone replacement therapy, his testosterone levels rise, which means more substrate available for aromatase, which means estrogen tends to rise as well. The standard response at many TRT clinics is to prescribe an aromatase inhibitor, something called anastrozole, which is a drug that blocks aromatase and directly reduces estrogen production. The logic sounds reasonable on the surface: high estrogen causes symptoms, so lower the estrogen.

But estrogen is not just a side effect to be managed. It is a required signal in the chain.

When you suppress estrogen with anastrozole, you pull the plug on the signal your liver needs to produce IGF-1. Research has shown that men given aromatase inhibitors experience significant drops in circulating IGF-1, because the liver is not getting the estrogenic stimulus it depends on to maintain production. One study found that estradiol is a primary regulator of hepatic IGF-1 gene expression, meaning the liver's instructions to make IGF-1 are written in estrogen. Remove the estrogen, the liver stops reading the instructions.

So the clinic has now sold you testosterone that raised your estrogen, then sold you anastrozole that crashed your estrogen and tanked your IGF-1, and now you have low IGF-1 levels and all the symptoms that come with that: poor recovery, reduced lean mass, fatigue, the things you came in hoping to fix.

What happens next is the part that should make you angry.

Instead of recognizing that the anastrozole caused the IGF-1 problem, the clinic identifies the low IGF-1 and offers you a solution: exogenous IGF-1 or growth hormone peptides to raise your levels back up. This is not medicine. This is a clinic selling you the problem and the treatment simultaneously, billing you for both, while your underlying hormonal axis remains broken.

The correct framing here matters. Estrogen in men is not a pathology. It is a functional signal. The goal of a well-managed testosterone protocol is not to drive estrogen as low as possible. It is to keep estrogen in a physiological range where it can do its job, which includes the IGF-1 signaling, bone density maintenance, cardiovascular protection, cognitive function, and libido, all of which are estrogen-dependent in men.

For most men on TRT, the answer to elevated estrogen is not an aromatase inhibitor. It is a reduction in testosterone dose, an adjustment in injection frequency, a change in administration route, or attention to body composition factors like adipose tissue that drive aromatase activity. Those changes cost nothing. Anastrozole costs something. And the downstream IGF-1 deficiency it creates costs even more.

The actual medical indication for exogenous IGF-1 is growth hormone deficiency caused by a non-functioning pituitary gland, a condition that is rare enough that most physicians who practice for an entire career will see it only a handful of times. The clinical guidelines for this are narrow and specific. You need a documented, confirmed deficiency from a malfunctioning pituitary, not a low IGF-1 reading on a lab that was suppressed by a drug the same clinic prescribed.

What TRT clinics are doing when they prescribe IGF-1 broadly is either operating outside the bounds of what the evidence supports, or they understand the mechanism and are using it to create a recurring revenue stream. Those are the only two options. Both are bad for the patient.

There is a version of this that men could avoid entirely by asking one question before accepting any new prescription: what caused this deficiency, and does that cause need to be treated, or does the treatment we already have need to be adjusted?

Low IGF-1 in a man on TRT with suppressed estrogen is not a peptide deficiency. It is an aromatase inhibitor problem. Treating it as a peptide deficiency while leaving the anastrozole in place means you will be chasing your own tail with your wallet open, because the drug that crashed the hormone is still running in the background.

The insight worth sitting with is this: the body does not have a testosterone system and an estrogen system and an IGF-1 system that operate independently. It has one integrated axis where each molecule is a signal to the next one downstream. When you block a signal in the middle of a chain, the end of the chain goes dark. Adding back what is missing at the end does not fix the chain. It just costs more money while the block remains in place. And any clinic that sells you the block and the bypass simultaneously, without ever explaining the connection, is not optimizing your hormones. They are monetizing your ignorance of how they work.

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