Evaluation of proteinuria and GFR to diagnose and classify kidney disease: systematic review and proof of concept.

Chronic kidney disease is often not associated with significant symptoms or abnormalities in common laboratory test results. Diagnosis is supposedly facilitated by calculating the glomerular filtration rate (GFR) from serum creatinine. A reference range GFR, however, does not exclude renal disease, because renal disease causes the subsequent decrease of renal function.