title: Chronic thromboembolic pulmonary hypertension is not associated with iron overload.
abstract: BACKGROUND
  Chronic thromboembolic pulmonary hypertension (CTEPH) is characterized as the incomplete resolution of emboli after pulmonary embolism (PE) and the subsequent fibrotic organization and remodeling of pulmonary vascular bed. It has been reported that abnormal fibrin probably contributes to the incomplete resolution of emboli. And there is evidence that free iron could convert fibrinogen into fibrin which is remarkably resistant to lysis. Thus, we hypothesized that persistent iron overload might participate in the development of CTEPH.
  
  
  METHODS
  A case-control study was conducted. Forty-five CTEPH patients were enrolled as cases, and 36 age and sex frequency-matched chronic PE patients without pulmonary hypertension were selected as controls. Levels of free iron, soluble transferrin receptor (sTfR), ferritin, sTfR/ferritin ratio, hepcidin-25, tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, and malondialdehyde (MDA) were compared between the two groups. Logistic regression analysis was carried out to estimate odds ratios.
  
  
  RESULTS
  There was no difference of the levels of free iron, hepcidin-25, sTfR, ferritin, sTfR/ferritin ratio, TNF-α, and MDA between CTEPH patients and the controls. Levels of sTfR and ferritin in both groups were within the normal limits. Levels of IL-6 in CTEPH patients were significantly higher than that in the controls. A negative correlation was observed between hepcidin-25 and sTfR (Spearman's r=-0.438, P<.001), and a positive correlation was observed between hepcidin-25 and ferritin (Spearman's r=0.503, P<.001). In the univariate logistic regression model, there was no association observed between CTEPH and free iron, hepcidin-25, sTfR, ferritin, sTfR/ferritin ratio, TNF-α, IL-6, and MDA.
  
  
  CONCLUSIONS
  CTEPH has no association with iron overload. The iron status evaluated by sTfR and ferritin is within the normal limits in this CTEPH population.
authors.affiliation: State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College; Center for Pulmonary Vascular Diseases, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College.
authors.forename: Qunying
authors.initials: Q
authors.lastname: Xi
authors.affiliation: Center for Pulmonary Vascular Diseases, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College. Electronic address: fuwaipumc@163.com.
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College; Center for Pulmonary Vascular Diseases, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College.
authors.forename: Weihua
authors.initials: W
authors.lastname: Liu
authors.affiliation: Center for Pulmonary Vascular Diseases, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College.
authors.forename: Zhihui
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: Center for Pulmonary Vascular Diseases, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College.
authors.forename: Qin
authors.initials: Q
authors.lastname: Luo
authors.affiliation: State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College; Center for Pulmonary Vascular Diseases, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College.
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Huang
mesh_terms: D016022:Case-Control Studies; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000209:etiology*; D019190:Iron Overload / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D011655:Pulmonary Embolism / Q000150:complications
keywords: Chronic thromboembolic pulmonary hypertension; Inflammation; Iron overload; Pulmonary embolism