Blood tests in the management of Helicobacter pylori infection

There are three main types of blood test available for the management ofHelicobacter pyloriinfection: those that detect an antibody response; tests of the pathophysiological state ofthe stomach; and those that indicate an activeinfection. Enzyme linked immunosorbent assay(ELISA) based kits are the most numerous ofthe commercially available tests. Originally thekits used crude antigen preparations but manyof the newer kits use a more purified antigenpreparation giving increased specificity but alower sensitivity. The sensitivity, specificity,and predictive values of the tests can also beaVected by the population under test andcoexistent disease in the patients. Near patienttest kits are based on either latex agglutinationor immunochromatography. Generally, theyhave low sensitivities compared with laboratorytests. Commerical western blotting kits havealso been developed and are used to detect thepresence of specific virulence markers. Theexact role of serology in the management ofHelicobacterinfection has still to be defined,although there is evidence that, used as ascreening procedure, it can reduce endoscopycost and workload. Gastrin and pepsinogenblood concentrations may provide valuableinformation on the pathophysiological state ofthe stomach—for example, the presence ofinflammation or gastric atrophy. A combination of serology and serum concentrations ofgastrin and pepsinogen may be used effectivelyto detect serious gastroduodenal disease inpatients.