Hey, I'm not a doctor, but I was once prescribed to lithium carbonate and a plethora of other meds... they used to think I was bipolar when I was a teenager, then they found out there's nothing wrong with me... Anyways, when I was taking the meds, there was a large emphasis placed on hydration because Lithium does MAJORLY impact your kidneys, and if you become too dehydrated you can contract lithium poisoning. Happened to me once at The Vans Warped tour... outside all day, got in a mosh pit, sweated something fierce... Next thing I knew I couldn't talk, couldn't walk, and my vision got blurry... woke up with an IV in the medical tent!
The point is, Lithium levels are largely controlled by the effectiveness of your kidneys... I can't say precisely how your wife's levels have been affected, I can only speculate, but if I were to speculate I would have to agree with the triage doctor and say that because of the bladder/kidney infection either her levels are too high or too low, but again I am not an expert. I would imagine that her levels will be tested, likely by doing some kind of bloodwork, and that when the analysis is complete they can give you the proper medical advice. I sincerely hope that you and your wife are doing ok! Seriously though, if such is the case and your wife's kidneys are apparently lax in their ability to properly regulate the lithium levels in her body and the problem persists, please be certain that a doctor checks out her kidneys. The LAST thing you want is renal failure or lithium poisoning. Don't stress it... there's no reason to lose sleep, just keep an eye out for it, no?