What causes proteinuria?
Protein should not normally appear in the urine in detectable quantities. It is usually kept in the blood by the filtering units (glomeruli) within the kidney. Proteinuria is an indicator that the kidneys are damaged in some way. Diseases that affect the filtering units themselves are the most common cause of heavy proteinuria. Sometimes this is called glomerulonephritis, meaning inflammation of the glomeruli. Just as some examples, any of the causes of nephrotic syndrome could be causes of proteinuria.
