Occasionally foamy urine is often caused by a fast urine stream or other factors and is not a cause for alarm, Mayo Clinic explains. However, persistently foamy urine is sometimes the result of excess protein in the urine, a condition that doctors call proteinuria.
Proteinuria sometimes indicates a serious kidney problem stemming from a medical condition such as diabetes or high blood pressure, says WebMD. Other conditions that cause protein to leak into the urine include trauma, toxins, infections, immune system disorders and the effects of some medications. Multiple myeloma and amyloidosis increase the production of proteins in the body and often result in proteinuria as well.