title: Does proteinuria-inducing physical activity increase biomarkers of acute kidney injury?
abstract: OBJECTIVE
  We sought to determine if an acute kidney injury biomarker, neutrophil gelatinaseassociated lipocalin (NGAL), would be up-regulated by high-intensity proteinuria-inducing exercise.
  
  
  METHODS
  A prospective cohort design was utilised. 100 healthy, active adults (mean age 24 ± 4 (SD) years) were screened for post-exercise proteinuria (PeP); 10 PeP positive and 10 PeP negative participants then completed a high-intensity exercise protocol involving an 800 meter sprint. Plasma and urinary NGAL, urinary creatinine, urinary albumin and urine volume were obtained at the following time points: pre-run, immediately post-, 25 minutes, one hour and two hours post-run.
  
  
  RESULTS
  Following high-intensity exercise, 64% of participants had urinary NGAL concentrations above the normal range, particularly at 25 minutes post (P = 0.002). However, there was no difference in NGAL response between PeP positive and negative groups and plasma NGAL was decreased, not elevated, following exercise (P = 0.002). In some individuals normalizing urinary NGAL for urinary creatinine attenuated elevations. Urinary NGAL was also negatively correlated with urine volume (r = -0.701, P = 0.005).
  
  
  CONCLUSIONS
  Proteinuria susceptibility did not influence an acute injury biomarker response to exercise. Nevertheless, urinary NGAL was elevated by exercise, possibly due to increased production by the proximal tubule, increased plasma clearance (given the decrease in plasma NGAL) and/or a concentrating effect of exercise-induced oliguria. Until correct normalisation of urinary biomarkers is determined, NGAL should be interpreted cautiously in exercise and acute kidney injury-induced oliguria. The inter-individual NGAL response to exercise also warrants further investigation.
authors.affiliation: College of Health and Behavioural Sciences, Bangor University, George Building, Bangor, Wales, LL57 2PZ, UK.
authors.forename: Naushad A
authors.initials: NA
authors.lastname: Junglee
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Lemmey
authors.forename: Megan
authors.initials: M
authors.lastname: Burton
authors.forename: Catrin
authors.initials: C
authors.lastname: Searell
authors.forename: Daniel
authors.initials: D
authors.lastname: Jones
authors.forename: Justin S
authors.initials: JS
authors.lastname: Lawley
authors.forename: Mahdi M
authors.initials: MM
authors.lastname: Jibani
authors.forename: Jamie H
authors.initials: JH
authors.lastname: Macdonald
mesh_terms: D058186:Acute Kidney Injury / Q000378:metabolism* / Q000503:physiopathology; D000209:Acute-Phase Proteins / Q000378:metabolism*; D000328:Adult; D000419:Albuminuria / Q000453:epidemiology / Q000652:urine; D015415:Biomarkers / Q000378:metabolism; D015331:Cohort Studies; D003404:Creatinine / Q000378:metabolism; D005260:Female; D006801:Humans; D015994:Incidence; D000071068:Lipocalin-2; D054834:Lipocalins / Q000378:metabolism*; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009846:Oliguria / Q000453:epidemiology / Q000378:metabolism; D011446:Prospective Studies; D011507:Proteinuria / Q000209:etiology* / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D015854:Up-Regulation / Q000502:physiology
chemical_list: D000209:Acute-Phase Proteins; D015415:Biomarkers; C489506:LCN2 protein, human; D000071068:Lipocalin-2; D054834:Lipocalins; D011518:Proto-Oncogene Proteins; D003404:Creatinine