..Just no.Yes i agree the body do control a lot of fhe actions on human body, but this is not something the human body controls. this justu is controled by the byakugou seal. And the byakugou seal is matined by chakra. regeneration is forced by this. even though this is medically impossible to surive, she surives it because it is forced. That is why the justu have such heavy drawbacks.
the reason she summoned katsuyu is not because of herself but because of the kages sake. If she just needed to heal herself she would have used regeneration. medical ninjutsu consumes to much chakra as it is regeneration is on another scale. The kages were her first concern so regeneration was out of the answer.
this pretty much sums it up.