title: Urine biomarkers of kidney injury among adolescents in Nicaragua, a region affected by an epidemic of chronic kidney disease of unknown aetiology.
abstract: BACKGROUND
  An epidemic of chronic kidney disease (CKD) of non-traditional aetiology has been recently recognized by health authorities as a public health priority in Central America. Previous studies have identified strenuous manual work, agricultural activities and residence at low altitude as potential risk factors; however, the aetiology remains unknown. Because individuals are frequently diagnosed with CKD in early adulthood, we measured biomarkers of kidney injury among adolescents in different regions of Nicaragua to assess whether kidney damage might be initiated during childhood.
  
  
  METHODS
  Participants include 200 adolescents aged 12-18 years with no prior work history from four different schools in Nicaragua. The location of the school served as a proxy for environmental exposures and geographic locations were selected to represent a range of factors that have been associated with CKD in adults (e.g. altitude, primary industry and CKD mortality rates). Questionnaires, urine dipsticks and kidney injury biomarkers [interleukin-18, N-acetyl-d-glucosaminidase (NAG), neutrophil gelatinase-associated lipocalin (NGAL) and albumin-creatinine ratio] were assessed. Biomarker concentrations were compared by school using linear regression models.
  
  
  RESULTS
  Protein (3.5%) and glucose (1%) in urine measured by dipstick were rare and did not differ by school. Urine biomarkers of tubular kidney damage, particularly NGAL and NAG, showed higher concentrations in those schools and regions within Nicaragua that were defined a priori as having increased CKD risk. Painful urination was a frequent self-reported symptom.
  
  
  CONCLUSIONS
  Although interpretation of these urine biomarkers is limited because of the lack of population reference values, results suggest the possibility of early kidney damage prior to occupational exposures in these adolescents.
authors: Preventive Medicine and Public Health Department, Universidad Autónoma de Madrid, Madrid, Spain Department of Epidemiology, Boston University School of Public Health, Boston, MA, USA.
authors: Oriana
authors: O
authors: Ramírez-Rubio
authors: Department of Epidemiology, Boston University School of Public Health, Boston, MA, USA.
authors: Juan José
authors: JJ
authors: Amador
authors: Research Service, VA New York Harbor Healthcare System and New York University School of Medicine, New York, NY, USA.
authors: James S
authors: JS
authors: Kaufman
authors: Division of Nephrology, Department of Medicine, Tufts Medical Center and Tufts University School of Medicine, Boston, MA, USA.
authors: Daniel E
authors: DE
authors: Weiner
authors: Section of Nephrology, Department of Medicine, Yale University, New Haven, CT, USA Program of Applied Translational Research, Department of Medicine, Yale University, New Haven, CT, USA.
authors: Chirag R
authors: CR
authors: Parikh
authors: Section of Nephrology, Department of Medicine, Yale University, New Haven, CT, USA Program of Applied Translational Research, Department of Medicine, Yale University, New Haven, CT, USA.
authors: Usman
authors: U
authors: Khan
authors: Department of Environmental Health, Boston University School of Public Health, Boston, MA, USA.
authors: Michael D
authors: MD
authors: McClean
authors: Department of Environmental Health, Boston University School of Public Health, Boston, MA, USA.
authors: Rebecca L
authors: RL
authors: Laws
authors: Department of Epidemiology, Boston University School of Public Health, Boston, MA, USA.
authors: Damaris
authors: D
authors: López-Pilarte
authors: Renal Division and Center for Vascular Biology Research, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors: David J
authors: DJ
authors: Friedman
authors: Renal Division and Center for Vascular Biology Research, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors: Joseph
authors: J
authors: Kupferman
authors: Department of Epidemiology, Boston University School of Public Health, Boston, MA, USA.
authors: Daniel R
authors: DR
authors: Brooks
mesh_terms: D000293:Adolescent; D015415:Biomarkers / Q000652:urine*; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D009527:Nicaragua / Q000453:epidemiology; D051436:Renal Insufficiency, Chronic / Q000453:epidemiology / Q000652:urine*; D012307:Risk Factors
chemical_list: D015415:Biomarkers
keywords: Mesoamerican Nephropathy; Nicaragua; adolescents; chronic kidney disease; urine biomarkers