I have a very non-threatening chronic kidney condition. One of the recommended management techniques is to drink a lot of liquids - this keeps my kidneys from retaining more water than they need to. The obvious downside is that I need to visit the bathroom semi-frequently (maybe 4ish times a day, but each visit is short).
Even if I am working at my desk and not in a meeting, I'm concerned this may be viewed as unprofessional behavior. I certainly don't want to cause any trouble at my workplace, but this is something recommended as a management technique by my nephrologist. I doubt the viability of carrying around a certificate from my Doctor and displaying it to all my coworkers on my way to the bathroom.
Meetings do not generally pose an issue, as longer meetings are usually scheduled in advance and will have a bathroom break at some point.