[1] Univ Naples Federico II, Sez Endocrinol, Dipartimento Med Clin & Chirurg, I-80131 Naples, Italy
[2] Univ Roma La Sapienza, Dept Expt Med, Rome, Italy
[3] Univ Sheffield, Sch Med, Dept Oncol & Metab, Sheffield, S Yorkshire, England
[4] Sheffield Teaching Hosp NHS Fdn Trust, Royal Hallamshire Hosp, Endocrine Unit, Sheffield, S Yorkshire, England
[5] Massachusetts Gen Hosp, Harvard Med Sch, Neuroendocrine Unit, Dept Med, Boston, MA 02114 USA