I have protein in urine but my liver and kidneys are ok?

Patient: I went to donate plasma and gave a urine sample. They said there was too much protein in it. I rarely eat red meat and a little chicken and most of my protein comes from nuts (but not enough to cause this) Ive read about the heart disease, UTI and Rheumatoid arthritis. I dont have a uti for sure, and Im going to see my doc about the other two. My reg doc ran blood screens and everything checked out ok, my kidney and liver are perfect. So what else could be causing this? Thanks in advance!

Doctor: Testing positive for protein in urine can indicate a kidney problem but not all the time. Sometimes, when the urine is i mproperly catched, too many cells can be sampled. These cells also contain proteinaceous material and can impart a false positive protein in urine. That could be your case since your doctor did further tests to assess your kidney and liver function and it turned out fine. I do hope I have appeased your concerns and take care always.