Persistently foamy urine that gradually becomes more noticeable may result from proteinuria, elevated protein levels in the urine, according to Mayo Clinic. Patients with foamy urine should consult a doctor immediately, as proteinuria can signal a severe kidney problem.
Occasional instances of foamy urine are generally not serious and may result from factors such as the speed of urine flow, states Mayo Clinic. In cases of proteinuria, albumin and other proteins leak through the kidney's damaged glomeruli into the urine, as confirmed by the National Kidney and Urologic Diseases Information Clearinghouse. This is a sign of chronic kidney disease, a condition commonly caused by diabetes or high blood pressure that may eventually lead to kidney failure.
Other symptoms of proteinuria may include swelling of the hands, feet, face or abdomen, as listed by the National Kidney and Urologic Diseases Information Clearinghouse. These symptoms occur when large amounts of protein in the blood are lost and often signal a progressed form of kidney disease. To test for proteinuria, a urine sample is taken to compare the level of albumin to the level of creatine in the urine. A blood test may also be needed. Because proteinuria often presents no symptoms, patients should receive regular urine checks to test for it.