I have been in remission a little over one year. I currently take 12.5mg of methotrexate once a week. I currently get lab work every 6 weeks. My most recent labs show a very high level of potassium. Can Methorexate cause high levels of potassium? I also take a prescription for folic acid. Can that affect potassium levels? I guess I'm looking for a cause that doesn't have to do with my kidneys (kidneys were not involved before).