1. Thyroid Unit, Massachusetts General Hospital, Boston, Massachusetts.
2. Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts.
3. Department of Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California.
4. Department of Surgery, Massachusetts General Hospital, Boston, Massachusetts.
5. Department of Surgery, Harvard Medical School, Boston, Massachusetts.
6. Department of Biostatistics and Epidemiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma.