1. Endocrinology Department, Hospital de Especialidades, Centro Médico Nacional Siglo XXI, IMSS, 06720 Mexico City, DF, Mexico
2. Faculty of Medicine, Universidad Nacional Autónoma de México (UNAM), 04510 Mexico City, DF, Mexico
3. Division of Medicine, Hospital de Especialidades, Centro Médico Nacional Siglo XXI, IMSS, 06720 Mexico City, DF, Mexico