I would have her checked out medically first. Having only one adrenal gland (if it is working properly) should not cause this, but you might want to rule out anything else.
As far as ADD symptoms go, it doesn't sound quite right. There must be clinical demonstration of attentional difficulties in multiple settings and during multiple activities. Can she sit through a TV show she likes? Does she pay attention during playtime? Is her attention span greatly out of the norm compared to other 5-year-olds? (I don't know many that can pay total attention in school).
The actual incidence of true ADD or ADHD in children is much MUCH lower than most people believe. Kids are hyper sometimes - they daydream - they goof off. All normal. Can you genuinely classify her behavior as being grossly outside of what is considered normal - - - or are you just a worried parent (which is understandable, given what you have been through already)...?