How Is Kidney Disease Diagnosed?
As with high blood pressure, you may not realize that you have kidney disease. Certain laboratory tests can indicate whether your kidneys are eliminating waste products properly. These tests include serum creatinine and blood urea nitrogen (BUN); elevated levels of either can indicate kidney damage. Proteinuria, an excess of protein in the urine, is also a sign of kidney disease.
Source: http://www.webmd.com