Kidneys filter the protein, sometimes dietary or globular protein leaks through when it isnt supposed to, this can be from several reasons.
Lanky is a dudes name, he posted in this thread.
Hepatic or renal problems= lower protein intake needed (damn near zero in some hepatic conditions....liver cant transdeaminiate the proteins properly).
Serum creatinine levels? I think its your protein intake, post the numbers of the blood/urine work, we need to see what else is going on there.