Helicobacter pylori Antibody, IgA, Serum
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Helicobacter pylori is a spiral-shaped, gram-negative bacillus that has been associated with gastritis, gastric and duodenal ulcers, and gastric malignancies.
Helicobacter pylori is found worldwide. In Caucasian populations in the United States and other industrialized countries, Helicobacter pylori infection is infrequent in childhood. Prevalence increases 0.5% to 2% with each year of age, reaching about 50% in those who are 60 or older. Prevalence rates appear to be higher in blacks and Hispanics than in whites. In a random population of 200 apparently healthy blood donors tested for Helicobacter pylori IgG antibody, the positive rate was 27.5% with an equivocal rate of 5.5%.
The diagnosis of Helicobacter pylori gastrointestinal disease is supported by the presence of serum antibodies: IgG, IgM, or IgA, to the organism. Screening patients for the presence of antibodies to Helicobacter pylori is a convenient, noninvasive means for assessing whether gastrointestinal symptoms may be related to Helicobacter pylori infection.
Because serology may lack specificity, additional noninvasive tests can be used to confirm Helicobacter pylori infection including the urease breath test (#81590 Helicobacter pylori Breath Test) or stool antigen test for Helicobacter pylori (#81806 Helicobacter Pylori Antigen, Feces). The gold standard for diagnosis of Helicobacter pylori disease is a biopsy of infected tissue and evaluating the tissue by Gram, silver, Giemsa, or acridine orange stains; or by immunofluorescence or immunoperoxidase methods; rapid urease testing; and/or culture.
Screening for Helicobacter pylori infection
Patients with Helicobacter pylori infection nearly always develop antibodies of the IgG class and less frequently develop antibodies of the IgA class. IgM antibodies may be produced shortly after the onset of infection. Levels of IgM antibodies should decrease after successful treatment, but may again increase if recurrence or relapse of infection occurs.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
This assay should be performed only on patients with gastrointestinal symptoms because of the large percentage of Helicobacter pylori-colonized individuals, especially in older age groups (estimated to be 40%-60% of asymptomatic Caucasians older than 60 years).
The serologic results must be interpreted in light of the clinical signs and symptoms of the patient.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Negative (Results with index value of <18.00 are negative.)
Equivocal (Results with index values of > or =18.00 but < or =20.00 are equivocal.)
Positive (Results with index values of >20.00 are positive.)
Clinical References Provides recommendations for further in-depth reading of a clinical nature
1. Blaser MJ: Helicobacter pylori and related organisms. In Principles and Practice of Infectious Diseases. Vol. 2. 4th edition. Edited by GL Mandell, R Dolin, JE Bennett. Churchill Livingstone Inc., 1995, pp 156-164
2. Perez-Perez GI, Taylor DN, Bodhidatta L, et al: Seroprevalence of Helicobacter pylori infections in Thailand. J Infect Dis 1990;29:2139-2143
3. Drumm B, Perez-Perez GI, Blaser MJ, et al: Intrafamilial clustering of Helicobacter pylori infection. N Engl J Med 1990;322:359-363
4. Morris AJ, Ali MR, Nicholson GI, et al: Long term follow-up of voluntary ingestion of Helicobacter pylori. Ann Intern Med 1991;114:662-663
5. Evans DJ Jr, Evans DG, Graham DY, et al: A sensitive and specific serologic test for detection of Campylobacter pylori infection. Gastroenterology 1989;96:1004-1008
6. Glassman MS, Dallal S, Berezin SH, et al: Helicobacter pylori related gastroduodenal disease in children. Diagnostic utility of enzyme-linked immunosorbent assay (ELISA). Dig Dis Sci 1990;35:993-997