[1] Univ Vermont, Lab Clin Biochem Res, Larner Coll Med, Burlington, VT 05405 USA
[2] Harvard Med Sch, Beth Israel Deaconess Med Ctr, Div Endocrinol Diabet & Metab, Boston, MA 02115 USA
[3] Dana Farber Canc Inst, Phyllis F Cantor Ctr Res Nursing & Patient Care, Boston, MA 02115 USA