[1] Kuopio Univ Hosp, Dept Med, POB 100, Kuopio 70029, Finland
[2] Univ Eastern Finland, Inst Clin Med Internal Med, Fac Med, Kuopio, Finland
[3] Univ Turku, Turku Univ Hosp, Lab Div, Clin Chem,Fac Med, Turku, Finland
[4] Eastern Finland Lab Ctr, Kuopio, Finland
[5] North Carelia Cent Hosp, Dept Med, Joensuu, Finland