Persistent high levels of protein in urine is a condition known as proteinuria and is usually caused by kidney disease. Proteinuria can also be caused by heart conditions, certain drugs, diabetes and pregnancy. Temporary proteinuria can occur due to fever, extreme temperatures, certain medications, stress and exercise, states Mayo Clinic.
Though there are many causes for proteinuria, WebMD recommends that doctors test for kidney disease if high levels of protein are found in urine. Kidney disease is often only found after discovering that a patient has proteinuria, because kidney disease often does not show any other early symptoms. If undiscovered or ignored, kidney disease can lead to kidney failure and death if not properly treated.
High blood pressure also causes proteinuria, according to the National Kidney and Urologic Diseases Information Clearinghouse. African Americans develop kidney failure related to hypertension at six times the rate of Caucasians, and American Indians, Hispanics and Pacific Islanders are also at a higher risk.
While the protein levels in urine are normally low, Mayo Clinic indicates it is also common for young, otherwise healthy people to have a urinalysis that reports a high count. Follow-up tests help determine if the report is a cause for concern.