1. Department of Medicine (N.E.C., C.Z., S.C.C., J.P.B.), Division of Endocrinology, College of Physicians and Surgeons, Columbia University, New York, New York 10032;
2. Department of Medicine (N.M.M.), Division of Mineral Metabolism, University of Texas Southwestern Medical Center, Dallas, Texas 75235;
3. Division of Medicine (P.Y.W., E.M.H., E.S.O.), Oregon Health and Science University, Portland, Oregon 97239;
4. Departments of Medicine and Epidemiology and Biostatistics (D.C.B.), University of California, San Francisco, San Francisco, California 94143