title: Delta-He: a novel marker of inflammation predicting mortality and ESA response in peritoneal dialysis patients.
abstract: BACKGROUND
  Inflammation impairs erythropoiesis, iron availability and is associated with a higher mortality risk in patients with end-stage renal disease. We studied the associations between Delta-He [the difference between the reticulocyte haemoglobin content (Ret-He) and erythrocyte haemoglobin content], a suggested marker of iron availability, and markers of inflammation, iron status, response to erythropoiesis-stimulating agents (ESAs) and mortality in prevalent peritoneal dialysis (PD) patients.
  
  
  METHODS
  Eighty-two PD patients were followed weekly for 12 weeks with an additional follow-up of 36 months. Delta-He, Ret-He and high-sensitivity C-reactive protein (hs-CRP) were measured weekly and interleukin-6 (IL-6) and iron markers every fourth week. Mortality risk was assessed by Cox proportional hazards model adjusting for potential confounding factors. The relationships between ESA response, inflammatory markers, iron markers and Delta-He were evaluated in the PD patients. The relationship between Delta-He and iron markers was analysed in 87 healthy subjects.
  
  
  RESULTS
  Delta-He correlated with IL-6 (rho = 0.48, P < 0.001), hs-CRP (rho = 0.36, P < 0.001) and ESA hyporesponsivess index (EHRI; rho = -0.44, P < 0.001) in the PD patients. Delta-He did not correlate with iron markers in PD patients nor in healthy subjects. The mean Delta-He levels were significantly different between the tertiles of EHRI (P < 0.01). Delta-He was associated with all-cause mortality risk in PD patients after adjusting for age, gender, hs-CRP, comorbidity and nutritional status [OR 0.70 (0.51-0.96), P < 0.05].
  
  
  CONCLUSIONS
  Delta-He independently predicts all-cause mortality in PD patients after adjusting for potential confounders and is a predictor of ESA response in PD patients.
authors: Institution of Laboratory Medicine , Karolinska Institutet , Stockholm , Sweden.
authors: Kristin
authors: K
authors: Danielson
authors: Institution of Laboratory Medicine , Karolinska Institutet , Stockholm , Sweden.
authors: Soheir
authors: S
authors: Beshara
authors: Division of Baxter Novum, CLINTEC, Department of Clinical Science, Intervention and Technology , Karolinska Institutet , Stockholm , Sweden ; Renal Medicine, CLINTEC , Karolinska institutet , Stockholm , Sweden.
authors: Abdul Rashid
authors: AR
authors: Qureshi
authors: Renal Medicine, CLINTEC , Karolinska institutet , Stockholm , Sweden.
authors: Olof
authors: O
authors: Heimbürger
authors: Division of Baxter Novum, CLINTEC, Department of Clinical Science, Intervention and Technology , Karolinska Institutet , Stockholm , Sweden ; Renal Medicine, CLINTEC , Karolinska institutet , Stockholm , Sweden.
authors: Bengt
authors: B
authors: Lindholm
authors: Institution of Laboratory Medicine , Karolinska Institutet , Stockholm , Sweden.
authors: Magnus
authors: M
authors: Hansson
authors: Renal Medicine, CLINTEC , Karolinska institutet , Stockholm , Sweden.
authors: Britta
authors: B
authors: Hylander
authors: Clinical Sciences, Danderyd Hospital , Karolinska Institutet , Stockholm , Sweden.
authors: Guna
authors: G
authors: Germanis
authors: Renal Medicine, CLINTEC , Karolinska institutet , Stockholm , Sweden.
authors: Peter
authors: P
authors: Stenvinkel
authors: Renal Medicine, CLINTEC , Karolinska institutet , Stockholm , Sweden.
authors: Peter
authors: P
authors: Barany
keywords: CRP; ESRD; IL-6; anaemia; erythropoietin; inflammation; iron; peritoneal dialysis