Project Summary: The candidate is a nephrologist starting a staff position at the Mayo Clinic on July 1st, 2006. During the past 4 years as a nephrology trainee, the candidate obtained a Master's degree in Clinical Research, first-authored 10 peer-reviewed articles, and received institutional (T32) and individual (F32) National Research Awards. His expertise in the epidemiology of chronic kidney disease and in kidney function methods has gained national attention. He was a grant reviewer for the Centers for Disease Control and Prevention and will moderate a symposium at the American Society of Nephrology Renal Week (2006). The environment will consist of Mayo Clinic - Rochester, where he will have a joint appointment in Nephrology and Epidemiology. His sponsor, Stephen Turner, M.D., Professor of Medicine, will provide him with access to data and train him to be an independent investigator. His mentorship team will also include two Professors of Epidemiology, an Associate Professor of Biostatistics, and the Co-director of the Renal Function Laboratory where 5500 'gold-standard'kidney function measurements are performed annually. The project will compare kidney function measurements between a gold standard method (iothalamate clearance) and more convenient, but potentially less accurate methods, used in clinical practice and in most studies (serum creatinine, cystatin C, estimating equations, and creatinine clearance). The unique feature of this project will be to compare these kidney function methods in community-based samples (mentor's cohort and candidate's cohort). The effect of the kidney function measurement method on coronary artery calcification and risk factor associations with chronic kidney disease will be determined. Relevence: In the United States, 8 million adults have moderate-to-severe reductions in kidney function and are at risk for costly morbid interventions (dialysis or transplantation) and cardiovascular disease. Validation of kidney function methods is needed to identify chronic kidney disease at an earlier stage, characterize its risk factors, and develop new treatment strategies.