TRT Clinics Are Selling You Hormonal Chaos

The liver makes IGF-1. That is not a controversial statement, and most people on testosterone replacement therapy have heard some version of it. But what almost nobody explains is why the liver makes IGF-1 in the first place, what controls that process, and why disrupting one part of the chain creates a cascade that eventually has you buying a peptide to fix a problem that was manufactured for you.

Start with the full picture before zooming in on any single piece.

Your body runs a hormonal axis that goes from the brain to the pituitary gland to the liver. The brain signals the pituitary, the pituitary releases growth hormone, and growth hormone travels to the liver where it triggers production of something called IGF-1, which stands for insulin-like growth factor 1 and is the molecule that actually does most of what people attribute to growth hormone itself. Tissue repair, muscle protein synthesis, recovery, the things people are chasing when they talk about growth hormone all run through IGF-1, not through growth hormone directly. Growth hormone is the messenger. IGF-1 is the worker.

That chain matters because it tells you where the intervention points are and where things can go wrong.

Now here is the part that gets left out of almost every TRT conversation. Estrogen is not just a female hormone that men need to suppress. Estrogen is one of the primary signals the liver uses to upregulate IGF-1 production. When estrogen is in a healthy range in a man, the liver is primed to respond to growth hormone and convert it into IGF-1. When estrogen drops, that conversion becomes blunted. The liver is still getting the growth hormone signal but producing less in response to it.

This is not theoretical. Studies in men with hypogonadism show that estrogen directly modulates hepatic IGF-1 output, and research in postmenopausal women given estrogen replacement shows IGF-1 levels rising in response, which is the clearest demonstration that the relationship is causal, not just correlated.

So now you understand the mechanism. And now the TRT clinic business model starts to make a different kind of sense.

You come in with low testosterone. They prescribe testosterone. Testosterone aromatizes, meaning it converts into estrogen through an enzyme called aromatase, which is normal and expected. Your estrogen goes up as your testosterone goes up. A lot of clinics then look at that rising estrogen number and treat it as a problem to be fixed, so they prescribe something called an aromatase inhibitor, most commonly anastrozole, which blocks aromatase and drops your estrogen levels. They are solving a lab value rather than a symptom, and in many cases they are creating a new problem in the process.

When your estrogen crashes, your liver loses one of its primary signals for IGF-1 synthesis. Your IGF-1 levels fall. You feel worse. Your recovery is poor, your body composition stalls, and you probably feel the kind of flat, low-energy, low-libido state that actually resembles low testosterone even though your testosterone number looks fine on paper.

You go back to the clinic and tell them you still feel bad.

And now they have a solution for that too.

They prescribe IGF-1 directly, either as the peptide itself or as something like mecasermin, which is a recombinant form developed for children with a specific condition called growth hormone insensitivity syndrome, a condition so rare that its entire clinical existence barely justifies the drug being manufactured at all. The actual FDA-approved use case for exogenous IGF-1 is primary IGF-1 deficiency caused by a non-functional growth hormone receptor, meaning the growth hormone signal is being sent but the cells cannot receive it. That condition affects an extraordinarily small number of people and has nothing to do with the population walking into TRT clinics.

What the clinic has done is create a deficiency through intervention and then sell you the fix for that deficiency.

The testosterone raised your estrogen. The anastrozole crashed your estrogen. The crashed estrogen reduced your IGF-1. The reduced IGF-1 created symptoms. The symptoms justified a new prescription. Every step of that chain generated a billable product or service, and none of it was necessary if the estrogen had simply been left in a healthy physiological range to begin with.

This is not a fringe critique. The clinical literature on testosterone replacement is fairly clear that estrogen management in men should be symptom-driven, not number-driven, and that many of the side effects attributed to high estrogen in men on TRT are actually caused by over-suppression rather than elevation. Estrogen in men supports bone density, cardiovascular function, cognitive performance, libido, and as now you know, IGF-1 production. Suppressing it aggressively does not create a more optimized hormonal environment. It creates a different set of deficiencies.

The practical implication here is straightforward. If you are on testosterone and your clinic wants to add anastrozole because your estrogen is elevated on a lab panel, the first question to ask is whether you are actually experiencing symptoms attributable to high estrogen. Not whether your number is above the reference range. Reference ranges for estrogen in men on testosterone replacement are not well established and are often carried over from ranges built for men not on exogenous testosterone, which is not a meaningful comparison. The second question is whether those symptoms might have another explanation before suppressing estrogen and triggering the downstream cascade described above.

And if someone is trying to sell you IGF-1 as a standalone peptide while your testosterone axis is not properly optimized, you are not buying a performance upgrade. You are paying to partially restore something that was working before they intervened.

The real insight here is that hormonal optimization, when done by someone who understands the system, should require fewer interventions over time, not more. Each hormone in the male axis modulates others, and the goal of genuine optimization is to stabilize that system at a point where it runs without constant management. What gets sold as optimization is often the opposite: deliberate destabilization that creates dependency on additional products to manage the symptoms of the last product. The body's hormonal network is not a series of independent dials you can turn up and down in isolation. It is a feedback system, and the way you know someone understands feedback systems is that their interventions make the system more stable, not less.

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