Clinical implication of immunoglobulin G levels in the management of patients with Helicobacter pylori infection.

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.

CONCLUSION

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.