Skierchick..You said you run and bike. How much do you do this, and in duration? I read your story and thought of rhabdomyolsis..the break down of muscle and is filtered thru the kidneys, and can read a positive blood. Usually it occurs with muscle damage from injuries, falls with remaining in one position for a long time, and that triatheletes/marathon runners are at risk for this. I am not a dr, nor do I play one so don't take my word for it..just a suggestion.