title: Serum KL-6 differentiates neuroendocrine cell hyperplasia of infancy from the inborn errors of surfactant metabolism.
abstract: BACKGROUND
  The study was conducted in order to determine if the glycoprotein KL-6 is a useful biomarker in differentiating neuroendocrine cell hyperplasia of infancy (NEHI), a benign form of children's interstitial lung disease, from the more severe inborn errors of surfactant metabolism (IESM), since their clinical presentation can be similar.
  
  
  METHODS
  Serum KL-6 levels were measured in 10 healthy control children, 6 with NEHI and 13 with IESM (4 with surfactant protein C (SP-C) and 9 with ABCA3 mutations). The initial clinical presentation, findings on previous CT scans and interstitial lung disease (ILD) scores at the time of KL-6 testing were compared. Correlations of KL-6 levels with age and with interval from lung biopsy were evaluated.
  
  
  RESULTS
  The median (range) KL-6 levels were 265 (1-409), 194 (47-352), 1149 (593-4407) and 3068 (726-9912) U/ml for the control, NEHI, SP-C and ABCA3 groups, respectively. When compared with the control and NEHI groups, median KL-6 levels were significantly higher in the SP-C (p<0.01; p = 0.01, respectively) and ABCA3 groups (p<0.001; p = 0.001, respectively); however, there was no difference between the control and NEHI groups (p = 0.91). An inverse relationship was seen between KL-6 levels and age in the IESM groups, but not in the NEHI or control groups. Children with NEHI had similar presenting clinical features and were equally symptomatic at the time of KL-6 measurement as those with IESM.
  
  
  CONCLUSIONS
  Children with NEHI have normal KL-6 levels, in contrast to those with IESM, who have elevated serum KL-6 levels; serum KL-6 may be a useful biomarker in distinguishing between these entities when their clinical presentations overlap.
authors.affiliation: Pediatric Pulmonary Section, Department of Pediatrics, Baylor College of Medicine,Texas Children's Hospital, 6621 Fannin, Houston, TX 77030, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: Doan
authors.forename: O
authors.initials: O
authors.lastname: Elidemir
authors.forename: M K
authors.initials: MK
authors.lastname: Dishop
authors.forename: H
authors.initials: H
authors.lastname: Zhang
authors.forename: E O
authors.initials: EO
authors.lastname: Smith
authors.forename: P G
authors.initials: PG
authors.lastname: Black
authors.forename: R R
authors.initials: RR
authors.lastname: Deterding
authors.forename: D M
authors.initials: DM
authors.lastname: Roberts
authors.forename: Q A
authors.initials: QA
authors.lastname: Al-Salmi
authors.forename: L L
authors.initials: LL
authors.lastname: Fan
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D000293:Adolescent; D015415:Biomarkers / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D006801:Humans; D006965:Hyperplasia / Q000378:metabolism / Q000473:pathology; D007223:Infant; D008052:Lipid Metabolism, Inborn Errors; D008168:Lung / Q000378:metabolism / Q000473:pathology*; D017563:Lung Diseases, Interstitial / Q000378:metabolism / Q000473:pathology*; D018396:Mucin-1 / Q000378:metabolism*; D055099:Neuroendocrine Cells / Q000378:metabolism / Q000473:pathology*; D037721:Pulmonary Surfactant-Associated Protein C / Q000235:genetics / Q000378:metabolism*
chemical_list: C441524:ABCA3 protein, human; D018528:ATP-Binding Cassette Transporters; D015415:Biomarkers; C060192:MUC1 protein, human; D018396:Mucin-1; D037721:Pulmonary Surfactant-Associated Protein C