T Nation

IGF-1 - GH Dose Response Analysis


I have two sets of IGF-1 lab results from two different doses.
First GH=0.9iu/day sc, IGF-1=204
Second GH=1.34iu/day sc, IGF-1=332 (GH dose is 57 % increased)

If you plot these two results you get a straight line that also intersects (0,0).

The IGF-1 dose response is linear. So one can get the slope of the line with only one data point, the first or latest lab result. In my case, the slope IGF-1:iu/day is 332/1.43=232.17. With this number, one can calculate what GH dose is required to achieve a given IGF-1 target. For me, a dose to achieve IGF-1=300 would be 300/232.17=1.292

Or if one wants to get to new dose, new_dose = old_dose *(target IGF-1 / current IGF-1)

IGF-1:iu/day GH will vary by ones weight [perhaps] but is mostly controlled by one's liver. And obviously, the potency of the GH is a major factor.

My AM cortisol improved/increased, now 19.3 [4-22]. Suspect that GH increased that.

Before starting rhGH my IGF-1 was 89.

Why 1.43 iu/day? Doc wanted 1.5iu/day. I can get 7 doses of 1.43iu out of a 10iu vial. If I took 1.5iu/day I would be near IGF-1=350 ng.ml

My analysis also indicated that my endogenous GH production was around 0.4iu/day. And the first 0.4iu of my dose simply replaces what I was making and is a benefit loss. Those most in need get the best cost benefit.


This is an old thread but are you still taking the GH? I’ve been curious about this myself - never had my IGF-1 tested but have been taking some MK677 which makes the pituitary pulse GH and I feel great.

I’ve read numerous conflicting studies on IGF-1 levels and cancer / mortality rates. It seems that mainstream medicine advocate keeping it at 150 or less, while anti aging docs think anything less than 300 is harmful.

What are your views on this?