So if IGF growth is permanent, then the results of the quoted study of the 28-year old male should have been permanent. Of course, they didn't do Penis Enlargement but we might draw a parallell to the use of IGF-1 for bodybuilding purposes; there is no permanent tissue growth there either, or should I say, the permanent tissue growth that I've read about has all been detrimental to overall health (enlargement of organs and such).