Abstract: Described is a method of detecting a protein fragment in a urine sample and a serum sample. The protein fragment is a urine precursor alpha-2-HS-glycoprotein, urine alpha-1 antitrypsin, urine alpha-1 acid glycoprotein, urine osteopontin, or serum osteopontin fragment. The urine sample and the serum sample are obtained from the same individual.