0-9
A B C D E F G H I J K L M N O
P Q R S T U V W X Y Z
  • No FAQs found
  • No FAQs found
  • No FAQs found
  • No FAQs found
  • No FAQs found
  • No FAQs found
  • No FAQs found

Helicobacter pylori (H pylori) Antibody Discontinuation

Test code(s) 17670(X), 17671(X), 17691(X), 20325, 29407, 29408(X), 34122, 34123, 37695, 40551, 40552

Question 1. Which tests have been used to diagnose H pylori?

Both invasive (endoscopic) and noninvasive diagnostic tests have been used. For patients undergoing endoscopy and gastric biopsy, H pylori culture with reflex to antibiotic susceptibility (test code 91245) may be considered as a useful means to diagnose active infection.

Noninvasive methods include stool antigen testing, urea breath testing, and serologic (antibody) assays. The latter are no longer recommended for the diagnosis of active infection.1,2

Stool antigen (test code 34838[X]) is detected using an enzyme immunoassay with a mixture of monoclonal anti-H pylori capture and detection antibodies. Detection of antigen indicates the presence of H pylori. Clinical sensitivity and specificity for diagnosis are both 96%. False-negative results may occur in patients receiving antimicrobials, proton pump inhibitors, and/or bismuth preparations within the previous two weeks; tests may be repeated two weeks after stopping these medications. Positive results are not affected by medications.

Because H pylori has high urease activity, the diagnosis may also be made through urea breath testing (14839[X]). H pylori-associated urease degrades the urea, producing ammonia and CO2. The resultant CO2 is absorbed in the blood and then exhaled. The CO2 is then measured in the patient’s breath. Clinical sensitivity and specificity for diagnosis are 97% and 95%, respectively.

Question 2. Why is Quest Diagnostics discontinuing H pylori antibody testing?

The American College of Gastroenterology (ACG) and the American Gastroenterology Association (AGA) guidelines no longer recommend the use of antibody testing for patients with H pylori active infection.1,2 Thus, effective October 19, 2015, Quest Diagnostics will no longer offer H pylori antibody (serology) testing.

Question 3. Which tests should be used in place of antibody tests?

Either the stool antigen or the urea breath test should be used in place of antibody tests.1,2

Question 4. What is the advantage of using the stool antigen or urea breath test instead of an antibody test?

Stool antigen and urea breath tests detect H pylori antigen and H pylori-associated urease, respectively. Both antigen and urease are present during infection, but not after resolution of the infection. Thus, these tests can be used to diagnose active infection and to document H pylori eradication after treatment.1,2

H pylori antibodies, on the other hand, occur both during and after infection. Antibody testing does not differentiate current (active) infection from past infection and thus has an inferior negative predictive value for diagnosis compared to stool antigen and urea breath tests. Furthermore, antibody tests have a poor positive predictive value in populations with low H pylori prevalence, eg, many areas in the United States. Finally, serology tests cannot be used to confirm eradication of infection after treatment.1,2

The ACG and AGA guidelines recommend using either stool antigen testing or urea breath testing as part of a test–treat–test approach to ensure appropriate therapy selection and eradication of H pylori infection.1,2

Confirmation of active infection allows judicious use of antimicrobials to treat only those patients who require therapy for active infection. This decreases costs, side effects (including sometimes significant gastrointestinal symptoms), and adverse events (including C difficile) associated with unnecessary antibiotic courses.

 H Pylori Antibodies Discontinuation FAQ Table

Question 5. What are the specimen collection requirements for the stool antigen test and the urea breath test?

Stool Antigen Test (test code 34838[X])

0.5 mL or 0.5 grams of semi-solid stool, or 20 mm diameter of solid stool, collected in a properly labeled plastic leak-proof container; specimen should be shipped refrigerated (up to 72 hours) or frozen (if delayed more than 72 hours).

Stool should not be placed in preservative, transport media, or swab. Watery stool is not acceptable.

Stability: room temperature, unacceptable; refrigerated, 72 hours; frozen, 30 days

Urea Breath Test (test code 14839[X] for adult patients and 92491 for patients aged 3-17 years)

Paired room-temperature breath samples (pre and post) collected in BreathTek™ UBT Collection Kit bags; follow instructions provided with kit. Provide gender, height, weight, and age for patients 3-17 years of age on the pediatric UHR card included in the BreathTek™ UBT Collection Kit.

 

References
 
  1. Chey WD, Wong BC, and Practice Parameters Committee of the American College of Gastroenterology. American College of Gastroenterology guideline on the management of Helicobacter pylori infection. Am J Gastroenterol. 2007;102(8):1808-1825. http://gi.org/guideline/management-of-helicobacter-pylori-infection/.
  2. Talley NJ, American Gastroenterological Association. American Gastroenterological Association medical position statement: evaluation of dyspepsia. Gastroenterology. 2005;129(5):1753-1755. http://www.gastrojournal.org/article/S0016-5085(05)01817-2/abstract.
This FAQ is provided for informational purposes only and is not intended as medical advice. A physician’s test selection and interpretation, diagnosis, and patient management decisions should be based on his/her education, clinical expertise, and assessment of the patient.
Document FAQS.171 Version: 0
Effective 10/19/2015 to present