Hormones like insulin, cortisol, and thyroxine have a narrow therapeutic index, meaning too much or too little is detrimental.

“is sort of the amazing thing with hormones like insulin and cortisol I'm always impressed by how tight the u-shape is on those curves Tyron hormone would be another example certainly less so with something like testosterone you have just a much wider range that you can function in and the benefit is largely monotonically increasing”