title: Iron metabolism in hemodialyzed patients - a story half told?
abstract: BACKGROUND
  All living organisms have evolved sophisticated mechanisms to maintain appropriate iron levels in their cells and within their body. Recently our understanding of iron metabolism has dramatically increased. Overt labile plasma iron (LPI) represents a component of non-transferrin bound iron (NTBI) that is both redox active and chelatable, capable of permeating into organs and inducing tissue iron overload. The LPI measures the iron-specific capacity of a given sample to produce reactive oxygen species. We studied for the first time NTBI correlations with markers of iron status and inflammation in prevalent hemodialyzed patients.
  
  
  METHODS
  Complete blood count, urea, serum lipids, fasting glucose, creatinine, ferritin, serum iron, total iron binding capacity (TIBC) were studied by standard laboratory method. The NTBI was assessed commercially available kits from Aferrix Ltd in Tel Aviv, Israel. A test result of 0.6 units of LPI or more indicates a potential for iron-mediated production of reactive oxygen species in the sample.
  
  
  RESULTS
  Patients with LPI units ≥ 0.6 had higher serum iron, erythropoiesis stimulating agents (ESA) dose, ferritin, high-sensitivity C-reactive protein (hsCRP), hepcidin and lower hemojuvelin. In hemodialyzed patients NTBI correlated with hsCRP (r = 0.37, p < 0.01), ferritin (r = 0.41, p < 0.001), IL-6 (r = 0.43, p < 0.001). In multivariate analysis predictors of NTBI were hemoglobin and alkaline phosphatase, explaining 58% of the variability.
  
  
  CONCLUSIONS
  Elevated NTBI in HD may be due to disturbed iron metabolism. Anemia and liver function might also contribute to the presence of NTBI in this population.
authors.affiliation: 2 Department of Nephrology, Medical University, Bialystok, Poland.
authors.forename: Jolanta
authors.initials: J
authors.lastname: Malyszko
authors.affiliation: 1 Department of Nephrology, Medical University, Bialystok, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Koc-Zorawska
authors.affiliation: The Chaim Sheba Medical Center, Tel Hashomer Hospital, Tel Aviv, Israel.
authors.forename: Nomy
authors.initials: N
authors.lastname: Levin-Iaina
authors.affiliation: Shaare Zedek Medical Center, Jerusalem, Israel.
authors.forename: Itzchak
authors.initials: I
authors.lastname: Slotki
authors.affiliation: Department of Nephrology, Internal Medicine and Dialysis Therapy, Warsaw Medical University, Warsaw, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Matuszkiewicz-Rowinska
authors.affiliation: 2 Department of Nephrology, Medical University, Bialystok, Poland.
authors.forename: Irena
authors.initials: I
authors.lastname: Glowinska
authors.affiliation: 1 Department of Nephrology, Medical University, Bialystok, Poland.
authors.forename: Jacek S
authors.initials: JS
authors.lastname: Malyszko
keywords: anemia; ferritin; hemodialysis; hepcidin; inflammation; iron metabolism; non-transferrin-bound iron