Scarring causes problems with the filtering process of the kidneys. This causes protein to leak from the blood into the urine, where it can be detected. Blood and urine tests can often diagnose this condition.
Glomerulosclerosis is just one of many possible causes of protein in the urine. You may need a kidney biopsy to confirm the diagnosis. In a biopsy, a tiny sample of kidney tissue is looked at under a microscope.