title: Erythropoietin concentration in acute kidney injury is associated with insulin-like growth factor-binding protein-1.
abstract: OBJECTIVE
  Erythropoietin (EPO) production is stimulated by hypoxia in the kidney. Ischaemic injury plays a crucial role in the pathogenesis of acute kidney injury (AKI). However, EPO concentrations in critically ill patients complicated with AKI have not been evaluated sufficiently. This study was conducted to clarify the factors associated with plasma EPO concentrations in AKI.
  
  
  METHODS
  This study prospectively enrolled 98 critically ill adult patients treated at the adult mixed ICU. Plasma EPO, insulin-like growth factor-binding protein-1 (IGFBP-1), neutrophil gelatinase-associated lipocalin (NGAL), interleukin-6 (IL-6) and urinary N-acetyl-β-D-glucosaminidase (NAG) were measured on ICU admission.
  
  
  RESULTS
  Acute kidney injury occurred in 42 (42.9%) patients. Significantly higher plasma EPO in the AKI group was detected than in the non-AKI group (16.13 (9.87-28.47) mIU/mL versus 27.81 (10.16-106.02) mIU/mL, P < 0.05). Plasma IGFBP-1 in the AKI group was also significantly higher than in the non-AKI group (19 208 (8820-50 780) pg/mL versus 63 199 (25 289-147 489) pg/mL, P < 0.05). Plasma EPO concentration was negatively correlated with haemoglobin in the non-AKI group with statistical significance, but not in the AKI group. Multiple logistic regression analysis revealed that plasma EPO in the AKI group was associated significantly with plasma IGFBP-1 and complication of diabetes mellitus, but not the haemoglobin concentration, partial pressure of arterial oxygen (PaO2 ), and IL-6.
  
  
  CONCLUSIONS
  Not low arterial oxygen tension, haemoglobin concentration, and inflammation evaluated by IL-6 but plasma IGFBP-1 was significantly associated with plasma EPO concentration in AKI, suggesting an unknown mechanism related to systemic stress conditions for EPO regulation in AKI.
authors.affiliation: Department of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan.
authors.forename: Tetsushi
authors.initials: T
authors.lastname: Yamashita
authors.affiliation: Department of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan.
authors.forename: Eisei
authors.initials: E
authors.lastname: Noiri
authors.affiliation: 22nd Century Medical and Research Center, The University of Tokyo, Tokyo, Japan.
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Hamasaki
authors.affiliation: Department of Emergency and Critical Care Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Takehiro
authors.initials: T
authors.lastname: Matsubara
authors.affiliation: Department of Emergency and Critical Care Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ishii
authors.affiliation: Department of Emergency and Critical Care Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Yahagi
authors.affiliation: Department of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan.
authors.forename: Masaomi
authors.initials: M
authors.lastname: Nangaku
authors.affiliation: Department of Emergency and Critical Care Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Kent
authors.initials: K
authors.lastname: Doi
mesh_terms: D058186:Acute Kidney Injury / Q000097:blood* / Q000175:diagnosis; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D016638:Critical Illness; D004921:Erythropoietin / Q000097:blood*; D005260:Female; D006801:Humans; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000097:blood*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015854:Up-Regulation
chemical_list: D015415:Biomarkers; C554270:EPO protein, human; C032231:IGFBP1 protein, human; D018970:Insulin-Like Growth Factor Binding Protein 1; D004921:Erythropoietin
keywords: acute kidney injury; biomarker; erythropoietin; insulin-like growth factor-binding protein-1