The present invention is directed to KIM-1 polypeptide as a plasma acute and chronic kidney injury and renal cell carcinoma biomarker, and methods and kits comprising the use of agents specific to KIM-1 for facilitating and enhancing the diagnosis of kidney injury or carcinoma. The present invention is based on the discovery that measuring KIM-1 levels in the blood is more accurate and reliable than measuring KIM-1 levels in the urine for the diagnosis of subjects with proximal kidney tubule injury or kidney cancer. The invention is directed to methods for diagnosis of acute kidney injury, chronic kidney disease (CKD), and renal cell cancer by determining and monitoring the levels of KIM-1 polypeptide in a blood sample, such as plasma or serum sample.
