Diagnosis of Helicobacter pylori Infection in Children: Is the ¹⁵N Urine Test More Reliable Than the ¹³C Breath Test?

Abstract

Background: The [¹³C]urea breath test is a convenient method to estimate Helicobacter pylori colonization non-invasively. As an alternative method, the [¹⁵N]urea urine test has been established. It is hypothesized that the urine test could be advantageous under some circumstances. The diagnostic value of the breath test might, for example, be jeopardized owing to fluctuating ¹³C isotope dilution by endogenous carbon dioxide. Methods: To compare the reliability and practicability of the two tests, ¹³C breath tests and ¹⁵N urine tests were performed simultaneously in three groups of patients: A) 36 adults under standardized conditions, B) 67 children who were allowed to move around during the test, and C) 18 children once without and once during standardized physical activity. Results: In the 36 adults there was a close correlation of the test results of the two methods (r = 0.88). In contrast, the correlation in the group of 67 children and infants was poor (r = 0.10). In the children with controlled activity the ¹³C results fluctuated, whereas the ¹⁵N results remained unchanged. Conclusions: Owing to their identical biochemical basis the breath test and the urine test produce the same diagnostic results in the same individuals if standardized pre-test and test conditions are followed. However, factors such as physical activity during the test may provoke fluctuations with a tendency to decreasing ¹³C values. This could be due to additional isotope dilution by increases in the endogenous production of ¹²C-carbon dioxide. We conclude that in very active children the ¹⁵N urine test might be advantageous and more reliable than the ¹³C breath test.