[1] Hosp Especialidades Ctr Med La Raza, Ctr Med Nacl Siglo 21, Endocrinol Unit, IMSS, Mexico City 115560, DF, Mexico
[2] Univ Michigan, Ann Arbor, MI 48109 USA
[3] Univ Sao Paulo, Sch Med, Hosp Clin, Sao Paulo, Brazil
[4] UBA, Hosp Clin Jose de San Martin, Buenos Aires, DF, Argentina
[5] Hosp San Juan Dios, San Jose, Costa Rica
[6] Univ Fed Rio de Janeiro, Rio De Janeiro, Brazil
[7] Inst Nacl Cancerol, Bogota, Colombia
[8] Hosp Gen Agudos Carlos G Durand, Div Endocrinol, Buenos Aires, DF, Argentina
[9] Univ Hosp, Caracas, Venezuela
[10] Inst Nacl Neurol & Neurocirug, Mexico City, DF, Mexico
[11] Univ Birmingham, Birmingham, W Midlands, England