I doubt that growth hormone would invariably result in acromegaly in an adult. It's possible, but it seems to me unlikely that it's inevitable.

I had an uncle who had a touch of acromegaly--large hands, stronger-than-normal features, hunched posture--and it was definitely from exposure to some kind of gas in WWI. I think Barry Brown tracked down Rondo Hatton's relatives--I know that he had a photo of Rondo relaxing on a lawn in Florida--who said that while in high school, Rondo was considered especially good-looking--and Barry had the high school photograph of Hatton to prove it.