title: Antistreptolysin O and anti-deoxyribonuclease B titers: normal values for children ages 2 to 12 in the United States.
abstract: BACKGROUND
  Measurement of antibodies to the extracellular antigens produced by group A streptococci, antistreptolysin O (ASO) and anti-deoxyribonuclease B (anti-DNase B), is often necessary to confirm a clinical diagnosis of a previous group A streptococcal infection, especially in patients suspected of having a nonsuppurative sequel to this infection. Age is among several factors that may influence antibody levels in children. Thus, in contrast to adults, what is considered a normal titer for one age group (infants) is not appropriate for another (older children). Age-related "normal" values for ASO and anti-DNase B are provided in the package inserts of commercially available kits; however, there are no recent comprehensive data to validate such values.
  
  
  OBJECTIVE
  Using sera from 1131 children (from 23 states) ages 2 to 12 years, we determined age-specific geometric mean titers (GMT) and upper limits of normal (ULN) of ASO and anti-DNase B.
  
  
  METHODS
  ASO and anti-DNase B titers were measured by conventional laboratory methods.
  
  
  RESULTS
  Children 7 years of age comprised the largest proportion (14%) of the study population. Approximately two-thirds of the sera were collected during winter and early spring months. For both ASO and anti-DNase B, both GMT values and ULN increased with age. The GMTs for ASO and anti-DNase B for the entire group of subjects were 89 and 112, respectively. The ULN for the entire group for ASO and anti-DNase B were 240 and 640, respectively.
  
  
  CONCLUSIONS
  The age-specific values for GMT and ULN for this group of children from 23 states were slightly higher than previously reported. These values are likely representative of the pediatric population in the United States and should be of clinical value to physicians, epidemiologists, and clinical laboratory personnel.
authors.affiliation: World Health Organization Collaborating Center for Reference and Research on Streptococci, Department of Pediatrics, University of Minnesota Medical School, Minneapolis, Minnesota, USA.
authors.forename: E L
authors.initials: EL
authors.lastname: Kaplan
authors.forename: C D
authors.initials: CD
authors.lastname: Rothermel
authors.forename: D R
authors.initials: DR
authors.lastname: Johnson
mesh_terms: D000367:Age Factors; D000906:Antibodies / Q000097:blood*; D001426:Bacterial Proteins; D002648:Child; D002675:Child, Preschool; D003851:Deoxyribonucleases / Q000276:immunology*; D006801:Humans; D012016:Reference Values; D013290:Streptococcal Infections / Q000175:diagnosis; D013297:Streptococcus pyogenes / Q000276:immunology*; D013301:Streptolysins / Q000276:immunology*; D014481:United States
chemical_list: D000906:Antibodies; D001426:Bacterial Proteins; D013301:Streptolysins; C025964:streptolysin O; D003851:Deoxyribonucleases; C020069:deoxyribonuclease B