If one were to only run higher HGH for a shorter period of 6mos or less, then drop to a dose that is <1.2 ULN, does that mitigate the risk? Or is there a permanent impact from the higher dose, even if not visible and if you ever resume at a higher dose, you are essentially picking up where you left off in terms of potential side effects?
There are a lot of variables. How high is high? How long?
Elevated bone turnover markers can appear within 2 weeks of supraphysiological levels of IGF, but it takes time for actual changes in bone structure to be detectable.
4x ULN. By 6 months most will experience initial irreversible bone changes. partially irreversible soft tissue changes occur earlier.
3x ULN. Stopping by 4 months would usually be completely reversible. But maybe not if you're "sensitive" to IGF.
Because effects require time to develop no matter how high the dose, 3 months at any level is going to be reversible within 3 to 4 months after returning 1x ULN. Seems to me if you want to run high doses safely, limit it to 3 months.
As far as "cycling", and whether it fully resets the "clock" of high dose overgrowth risk., we're moving into territory there's no good scientific info on, because it doesn't resemble anything like the way medicine uses rHGH, or acromegaly works in folks with that disorder,
We're on our own, and all I can do is draw conclusions from the mechanisms of action.
So yes, if you run 15iu a day for 3 months hitting 4x ULN IGF-1, any changes you observe will fully reverse 3-4 months after returning to below the ULN.
However, without getting excessively technical, suffice to say the groundwork for undesirable changes has been laid, in bone, cartilage, and organs, It's work that won't have to be repeated on the next high dose cycle. Like pouring a foundation, starting to construct a building, and during the break back to normal IGF, tearing down the frame you started to build, but the foundation is still there. So to some extent, the next cycle is picking up where the last one left off.
Are 2x 3 month high dose cycles with a 3 month break better than a single 6 month run. Yes.
Could you keep doing this without seriously risking acromegaly. No. Each cycle is cumulatively increasing risk. Not as fast as continuous high IGF, but it's increasing with each cycle.
My guess is we'll eventually see some "Cumulative exposure over X years limit. IE over 5 years no more than 6 months total exposure at 4x ULN (no more than 3 months in a row without a break), 12 months at 3x (no more than 6 months in a row), 18 months at 2x (no more than 9 months), 36 at 1.5x (no more than 18 months), continuous use below 1.3x.
These are (mostly) arbitrary exposure limits (except below 1.3x indefinite), but I think a useful way to think about running high doses until we get more info on long term use at supraphysiological IGF levels.