title: Plasma catalytic iron, AKI, and death among critically ill patients.
abstract: OBJECTIVE
  Catalytic iron has been hypothesized to be a key mediator of AKI. However, the association between plasma catalytic iron levels and AKI has not been well studied in humans.
  
  
  METHODS
  A single-center, prospective, nonconsecutive cohort study of 121 critically ill patients admitted to intensive care units (ICUs) between 2008 and 2012 was performed. Plasma catalytic iron, free hemoglobin, and other iron markers were measured on ICU days 1 and 4. The primary end point was in-hospital mortality or AKI requiring RRT. Secondary end points included mortality (assessed during hospitalization, at 30 days, and 1 year) and incident AKI, defined by modified Kidney Disease Improving Global Outcomes criteria.
  
  
  RESULTS
  ICU day 1 plasma catalytic iron levels were higher among patients who reached the primary end point (median, 0.74 µmol/l [interquartile range, 0.31-3.65] versus 0.29 µmol/l [0.22-0.46]; P<0.01). ICU day 1 plasma catalytic iron levels were associated with number of packed red blood cell transfusions before ICU arrival (rs=0.29; P<0.001) and plasma free hemoglobin levels on ICU day 1 (rs=0.32; P<0.001). Plasma catalytic iron levels on ICU day 1 were significantly associated with in-hospital mortality or AKI requiring RRT, even after adjusting for age, enrollment eGFR, and number of packed red blood cell transfusions before ICU arrival (13 events; adjusted odds ratio per 1-SD higher ln[catalytic iron], 3.33; 95% confidence interval, 1.79 to 6.20). ICU day 1 plasma catalytic iron levels were also significantly associated with incident AKI, RRT, hospital mortality, and 30-day mortality.
  
  
  CONCLUSIONS
  Among critically ill patients, elevated plasma catalytic iron levels on arrival to the ICU are associated with a greater risk of incident AKI, RRT, and hospital mortality.
authors.affiliation: Division of Renal Medicine, Brigham and Women's Hospital, Boston, Massachusetts; and DELEAF@partners.org.
authors.forename: David E
authors.initials: DE
authors.lastname: Leaf
authors.affiliation: Department of Nephrology.
authors.forename: Mohan
authors.initials: M
authors.lastname: Rajapurkar
authors.affiliation: Department of Cardiology, Muljibhai Patel Urological Hospital, Gujarat, India.
authors.forename: Suhas S
authors.initials: SS
authors.lastname: Lele
authors.affiliation: Department of Nephrology.
authors.forename: Banibrata
authors.initials: B
authors.lastname: Mukhopadhyay
authors.affiliation: Division of Renal Medicine, Brigham and Women's Hospital, Boston, Massachusetts; and.
authors.forename: Sushrut S
authors.initials: SS
authors.lastname: Waikar
mesh_terms: D058186:Acute Kidney Injury / Q000097:blood* / Q000401:mortality* / Q000628:therapy; D000368:Aged; D002384:Catalysis; D003422:Critical Care; D016638:Critical Illness; D017707:Erythrocyte Transfusion; D005260:Female; D005293:Ferritins / Q000097:blood; D006454:Hemoglobins / Q000378:metabolism; D017052:Hospital Mortality; D006801:Humans; D015994:Incidence; D007501:Iron / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D017582:Renal Replacement Therapy; D013997:Time Factors
chemical_list: D006454:Hemoglobins; D005293:Ferritins; D007501:Iron
keywords: ARF; mortality; outcomes