[1] Karolinska Univ Hosp, Dept Clin Chem, Stockholm, Sweden
[2] Univ Med, Gottingen, Germany
[3] Univ Med, Inst Clin Chem & Lab Med, Greifswald, Germany
[4] Linkoping Univ, Dept Clin Chem, Linkoping, Sweden
[5] Linkoping Univ, Dept Clin & Expt Med, Linkoping, Sweden