title: Serum KL-6 levels in pediatric patients: reference values for children and levels in pneumonia, asthma, and measles patients.
abstract: Serum KL-6 reflects alveolar damage and regeneration of type II pneumocytes, indicating disease activity in various interstitial lung diseases. We conducted a descriptive and observational multiple case-control study to determine the distribution of serum KL-6 levels in pediatric patients with or without respiratory diseases. Subjects were recruited from the patients of a teaching hospital in the suburb of Tokyo. A consecutive series of 401 children (0-16 years old) underwent blood sampling for many clinical reasons. They comprised the following four groups: pneumonia (n = 96), bronchial asthma (n = 101), measles (n = 102), and nonrespiratory diseases (n = 102) as a control group. Standard upper limits of serum KL-6 in a group of children with nonrespiratory disease were 250 U/mL, or half the adult level. No gender or age differences were observed. Elevated serum KL-6 concentrations were observed in severe pneumonia, acute exacerbations of asthma, and measles pneumonia. In the measles group, KL-6 values reflected the presence and severity of complicating pneumonia. We conclude that serum KL-6 levels exceeding 250 U/mL were rarely observed in children without respiratory diseases. In contrast, a substantial proportion of children with common respiratory diseases showed mild to moderate increases in serum KL-6 levels. Elevated serum KL-6 in these children may reflect the presence of alveolar damage, followed by regeneration of type II pneumocytes. However, in order to use serum KL-6 as a marker of interstitial lung diseases in children, a cutoff level should be determined separately.
authors.affiliation: Department of Pediatrics, Nippon Medical School, Tokyo, Japan. takehide@nms.ac.jp
authors.forename: Takehide
authors.initials: T
authors.lastname: Imai
authors.forename: Masato
authors.initials: M
authors.lastname: Takase
authors.forename: Sachiyo
authors.initials: S
authors.lastname: Takeda
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Kougo
mesh_terms: D000293:Adolescent; D000941:Antigens / Q000097:blood*; D000951:Antigens, Neoplasm; D001249:Asthma / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000032:analysis; D002648:Child; D002675:Child, Preschool; D005260:Female; D006023:Glycoproteins / Q000097:blood*; D006801:Humans; D007223:Infant; D007770:L-Lactate Dehydrogenase / Q000097:blood; D007962:Leukocytes / Q000737:chemistry; D008297:Male; D008457:Measles / Q000097:blood* / Q000150:complications; D018396:Mucin-1; D009077:Mucins; D011014:Pneumonia / Q000097:blood* / Q000145:classification / Q000175:diagnosis / Q000209:etiology; D011650:Pulmonary Alveoli / Q000378:metabolism; D012016:Reference Values; D012680:Sensitivity and Specificity
chemical_list: D000941:Antigens; D000951:Antigens, Neoplasm; D015415:Biomarkers; D006023:Glycoproteins; C060192:MUC1 protein, human; D018396:Mucin-1; D009077:Mucins; D002097:C-Reactive Protein; D007770:L-Lactate Dehydrogenase