Someone with consistently high protein in the urine may have kidney disease, but other causes could include a buildup of abnormal proteins in the organs called amyloidosis, diabetes, hypertension, Hodgkin's disease or sickle cell anemia, states Mayo Clinic. High protein may also result from leukemia, lupus, heart disease or pregnancy.
Kidneys filter waste from the blood and keep proteins. When certain disorders permit proteins to pass through the kidneys into the urine, it is called proteinuria, notes Mayo Clinic. Increasing amounts of protein in a diabetic patient's urine may indicate diabetic kidney damage. However, temporarily high protein levels are not unusual and can occur after vigorous exercise, fever or illness, or with exposure to heat or cold.