Here is a quote from Wikipedia - Proteinuria (/prəʊtiː'n(j)ʊəriə/, from protein and urine) means the presence of an excess of serum proteins in the urine
. The protein in the urine
often causes the urine
to become foamy, although foamy urine
may also be caused by bilirubin in the urine (bilirubinuria), retrograde ejaculation, pneumaturia (air bubbles in the urine) due to a fistula, or drugs such as pyridium. http://en.wikipedia.