I'm vegan with proteinuria? Is this a sign of kidney failure?

I've been vegan for a little over a year. I have cheated on multiple occasions with fish, but have had minimal cheese, milk, eggs and virtually no red meat. I recently went to the doctor who said that I had proteinuria (protein in my urine). She took a blood test and assured me that it wasn't leukemia. But I'm a little worried that it might be something serious. Help?