Proteinuria: Medical term derived from the Greek protos, first, for being the protein one of the first organic elements with carbohydrate and carbs and ouron ourou, urine. Excessive presence of protein in the urine by the abnormal functioning of the kidney. The presence of more than 8 milligrams is considered excessive per deciliter. It should be considered a serious health problem often associated with diabetes, high blood pressure or kidney disease.