[1] Uppsala Univ, Univ Hosp, Dept Med Sci, S-75185 Uppsala, Sweden
[2] Landspitali Univ Hosp, Dept Allergy Resp Med & Sleep, IS-108 Reykjavik, Iceland
[3] Univ Iceland, Fac Med, IS-101 Reykjavik, Iceland
[4] Iceland Heart Assoc, IS-201 Kopavogur, Iceland
[5] Landspitali Univ Hosp, Dept Clin Biochem, IS-101 Reykjavik, Iceland
[6] Landspitali Univ Hosp, Dept Gastroenterol, IS-101 Reykjavik, Iceland