... 3Research articleIncreased serum HO-1 in hemophagocytic syndrome and adult-onset Still's disease: use in the differential diagnosis of hyperferritinemiaYohei Kirino1, Mitsuhiro Takeno1, ... YK, MT, and MI, con-ducted the laboratory work. YK, MT, AU, SO, AS, HK, KT, and YI were involved in the analysis and interpretation of data. YK,MT, and YI were involved in writing the report. ... levelswould be useful in the differential diagnosis of hyperferritinemia and perhaps also in monitoring disease activity in HPS and ASD.IntroductionHeme oxygenase (HO) is an enzyme that catalyzes the...