title: Clinical implication of immunoglobulin G levels in the management of patients with Helicobacter pylori infection.
abstract: OBJECTIVE
  The objective of this research was to gauge the diagnostic utility of serology tests compared with urea breaths tests (UBTs) and determine reliable threshold values/ranges for diagnosis of Helicobacter pylori infection using only immunoglobulin (Ig) G results.
  
  
  METHODS
  Data were obtained from 371 patients with UBTs and/or serology tests. Quantitative results were converted to multiple of minimum positive value (MMPV). Results were paralleled to obtain percentage change in serum IgG levels and 95% confidence intervals were obtained to establish new ranges for diagnosis.
  
  
  RESULTS
  Treated patients with only serology tests in a time frame of 3 to 6 months after final treatment displayed a 68.33% ± 2.95% decrease in 95% confidence interval of serum IgG. Uninfected patients with serology and UBT results within 2 weeks displayed a range of 1.32 ± 0.23 MMPV; infected patients produced a range of 3.32 ± 0.88 MMPV.
  
  
  CONCLUSIONS
  Treated patients should display a 65.38% to 71.28% decrease in serum IgG levels, along with an ending IgG level of ≤1.75 U/mL or ≤4.025 EV (ELISA value). Before treatment or exposure, patients with serum IgG values of 1.09 to 1.55 U/mL or 2.507 to 3.565 EV or lower are generally uninfected. Because of the lower cost and high confidence of results, we believe that IgG testing should be considered as a reasonable and even perhaps preferred method of monitoring H. pylori infections.
authors.affiliation: From the College of Natural Sciences, University of Texas at Austin, Austin (DW); the Department of Internal Medicine, Louisiana State University Science Center, Shreveport (TC); and Plano Family Medicine, Plano, TX (K-WC). Dw050493@gmail.com.
authors.forename: Daniel
authors.initials: D
authors.lastname: Wang
authors.affiliation: From the College of Natural Sciences, University of Texas at Austin, Austin (DW); the Department of Internal Medicine, Louisiana State University Science Center, Shreveport (TC); and Plano Family Medicine, Plano, TX (K-WC).
authors.forename: Timothy
authors.initials: T
authors.lastname: Chiu
authors.affiliation: From the College of Natural Sciences, University of Texas at Austin, Austin (DW); the Department of Internal Medicine, Louisiana State University Science Center, Shreveport (TC); and Plano Family Medicine, Plano, TX (K-WC).
authors.forename: Kwok-Wai
authors.initials: KW
authors.lastname: Chiu
mesh_terms: D001944:Breath Tests; D005260:Female; D016481:Helicobacter Infections / Q000175:diagnosis* / Q000276:immunology; D016480:Helicobacter pylori / Q000276:immunology* / Q000302:isolation & purification; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012698:Serologic Tests
chemical_list: D007074:Immunoglobulin G
keywords: Cancer; Cost Effectiveness; Evidence-Based Medicine; Gastric Ulcer; Gastrointestinal Diseases; Helicobacter pylori