I've had blood in my urine since 9th grade, i'm now a sophomore in college and still have it. It doesn't matter if i run hard or run easy, run long or short. I have had exploratory surg. and they found no tumors or n e thing of the such. my urine contains a very abnormal load of protein in it the doctors say that it is toxic to the kidneys and its pretty much pure meet cells and protien in my urine. They told me to stop running 3 years ago and i am still going strong and i keep improving every year.