title: Circadian variation of urinary eosinophil protein X in asthmatic and healthy children.
abstract: BACKGROUND
  It is suggested that urinary eosinophil protein X (EPX) is a noninvasive tool to monitor bronchial inflammation in asthmatic children. However, circadian variation of the number and activation of eosinophils might possibly influence urinary EPX excretion.
  
  
  OBJECTIVE
  Measurements of urinary EPX (radioimmunoassay) were used to investigate circadian variation of eosinophilic activation and to monitor bronchial inflammation in children with asthma before and after treatment with corticosteroids.
  
  
  METHODS
  Urinary EPX excretion (microg/mmol creatinine) was measured in the morning and afternoon in 22 stable asthmatics and in 16 nonatopic, nonasthmatic controls to investigate circadian variation. Additionally, EPX excretion in the afternoon was analysed in 21 children with chronic asthma before and after 6 weeks of treatment with inhaled corticosteroids, and in seven children within 24 h of admission due to an asthma exacerbation and again 3 months after discharge.
  
  
  RESULTS
  EPX excretion in the first morning urine sample of the day compared with the afternoon urine sample was significantly higher both in children with asthma (n = 22; mean +/- standard deviation: 179.7 +/- 97.3 vs 60.9 +/- 40.7 microg/mmol creatinine, P = 0.0001) and in nonatopic nonasthmatic controls (n = 16; 114.5 +/- 57.1 vs 53.4 +/- 29.0 microg/mmol creatinine, P = 0.0001). EPX excretion decreased significantly after 6 weeks of anti-inflammatory treatment in the group of children with chronic asthma (n = 21; 124.7 +/- 84.6 vs 87. 5 +/- 61.9 microg/mmol creatinine, P = 0.02) and in the group of children with an acute asthma exacerbation 3 months after discharge (n = 7; 233.2 +/- 174.5 vs 75.8 +/- 59.5 microg/mmol creatinine, P = 0.02).
  
  
  CONCLUSIONS
  This study suggests a circadian variation of EPX excretion in children with asthma and in nonatopic, nonasthmatic controls. Measurement of EPX excretion is helpful monitoring therapy in asthmatic children if circadian variation is considered.
authors.affiliation: University Children's Hospital Freiburg, Freiburg, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Storm van's Gravesande
authors.forename: J
authors.initials: J
authors.lastname: Mattes
authors.forename: T
authors.initials: T
authors.lastname: Grüntjens
authors.forename: M
authors.initials: M
authors.lastname: Kopp
authors.forename: H H
authors.initials: HH
authors.lastname: Seydewitz
authors.forename: M
authors.initials: M
authors.lastname: Moseler
authors.forename: J
authors.initials: J
authors.lastname: Kuehr
mesh_terms: D000293:Adolescent; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use; D001249:Asthma / Q000188:drug therapy / Q000276:immunology / Q000652:urine*; D001798:Blood Proteins / Q000652:urine*; D019819:Budesonide / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D002940:Circadian Rhythm; D047208:Eosinophil-Derived Neurotoxin; D004804:Eosinophils / Q000276:immunology; D005260:Female; D006801:Humans; D008297:Male; D012260:Ribonucleases
chemical_list: D000893:Anti-Inflammatory Agents; D001798:Blood Proteins; D019819:Budesonide; D047208:Eosinophil-Derived Neurotoxin; D012260:Ribonucleases