[1] Birmingham Childrens Hosp, Dept Endocrinol, Birmingham B4 6NH, W Midlands, England
[2] Amer Univ Beirut, Calcium Metab & Osteoporosis Program, Lebanon, NH USA
[3] Stanford Univ, Dept Med, Palo Alto, CA 94304 USA
[4] UCL Inst Child Hlth, Dept Nutr & Surg Sci, London, England
[5] Nemours AI duPont Hosp Children, Dept Res, Wilmington, DE USA
[6] Childrens Mem Hlth Inst, Dept Biochem & Expt Med, Warsaw, Poland
[7] Brown Univ, Hasbro Childrens Hosp, Div Adolescent Med, Providence, RI 02912 USA
[8] Brown Univ, Alpert Med Sch, Providence, RI 02912 USA