[1] Haukeland Hosp, Lab Clin Biochem, N-5021 Bergen, Norway
[2] Zuyderland Med Ctr, Dept Clin Chem, Heerlen, Netherlands
[3] Imperial Coll London, St Marys Hosp, Diabet Endocrinol & Metab, London, England
[4] AZ St Jan Hosp, Dept Lab Med, Brugge, Belgium
[5] Hop La Chartreuse, Lab Biol Polyvalente, Villefranche De Rouergue, France
[6] St Vincents Univ Hosp, Dept Clin Chem, Dublin, Ireland
[7] Leeds Gen Infirm, Blood Sci, Leeds, W Yorkshire, England