My Wife Was Diagnosed With Gbm Jan 4 2016. Started

My wife was diagnosed with gbm Jan 4 2016. Started chemo and radiation last Thurs. We were just contacted by an assistant to the Nuero doctor and told her potassium level was high without any kind of explanation at all. Obviously this was a concern or we wouldn't have got the call. Could you explain why? She does have a doctors appointment tomorrow but was just wondering tonite.