What causes protein in urine and low bun?

Proteinuria, low BUN. Proteinuria (p) needs to be quantified. This can be done with a 24 hour urine collection that will measure p as well as the renal function of a patient. Blood work (bw) will need to be taken. If the p > 1 gram/day, and bw does not give the p's cause, a kidney biopsy may be needed. Low BUN levels may be reflection of a low protein intake or over-hydration. See a nephrologist for more info.