Helicobacter pylori serology at diagnosis and follow-up of biopsy-verified infection in children.

Data on the use of Helicobacter pylori serology in children are limited. We studied the serum antibodies of 105 H. pylori-infected children (median age 9.1 y, range 1.5-17.5 y) using an in-house enzyme immunoassay. At diagnosis of the biopsy-verified infection, IgG antibodies to H. pylori were elevated in 98/105 children (93%) but were at a normal level in 7 children, 5 of whom were < 5 y of age. Serum IgA antibodies to H. pylori were elevated in 40/105 children (38%). The levels of IgG and IgA antibody titers to H. pylori correlated with age (p < 0.001 and p < 0.02, respectively). IgG titers were reduced by > or = 50% in 85% (83/98; median follow-up 0.6 y) of children after therapy. In 56 such children eradication was verified by negative histology or urea breath test but I such child showed Helicobacters on histologic examination. Of the 15 children whose IgG titers dropped by < 50%, 7 were considered positive and 4 negative on the basis of histology or urea breath test. In 3 children, IgG titers returned to pretreatment levels 1 y after a 50% drop was seen. Serology is 1 alternative for monitoring H. pylori infection in children, although its sensitivity is lower in very young children. The length of follow-up needed after eradication, however, is unclear.