Sensitivity and specificity of an abbreviated ¹³ C‐mixed triglyceride breath test for measurement of pancreatic exocrine function

Abstract

Background: A modified 13 C-mixed triglyceride breath test ( 13 C -MTGT) detects moderate pancreatic exocrine insufficiency noninvasively and reliably, but it requires prolonged breath sampling (6 hours (hr)). Objective: We aimed to investigate whether 13 C -MTGT can be abbreviated, to optimize clinical usability. Methods: We analyzed the 13 C-MTGT of 200 consecutive patients, retrospectively. Cumulative 1-5 hr 13 C-exhalation values were compared with the standard parameter (6-hr cumulative 13 C-exhalation). We determined the sensitivity and specificity of shortened breath sampling periods, by comparison with the normal values from 10 healthy volunteers, whom also underwent a secretin test to quantitate pancreatic secretion. Moreover, we evaluated the influence of gastric emptying (GE), using a 13 C-octanoic acid breath test in a subset (N ¼ 117). Results: The 1-5 hr cumulative 13 C-exhalation tests correlated highly and significantly with the standard parameter (p < 0.0001). Sensitivity for detection of impaired lipolysis was high (!77%), but the specificity was low (!38%) for the early measurements. Both parameters were high after 4 hrs (88% and 94%, respectively) and 5 hrs (98% and 91%, respectively). Multivariate linear correlation analysis confirmed that GE strongly influenced early postprandial 13 C-exhalation during the 13 C-MTGT. Conclusion: Shortening of the 13 C -MTGT from 6 to 4 hrs of duration was associated with similar diagnostic accuracy, yet increased clinical usability. The influence of GE on early postprandial results of the 13 C-MTGT precluded further abbreviation of the test.

Diagnosis of Exocrine Pancreatic Insufficiency

“…Although this test is appealing as a non-invasive test, it requires a substantial time investment from patients (6-8 h) in which they can only have limited activity. A recent study suggested the diagnostic accuracy remains good (sensitivity 88 % and specificity 94 %) when an abbreviated 4 h test was performed, but this requires further validation [24]. The largest problem with the MTBT is that the radiolabelled tracers required for the study are not available worldwide.…”

“…Over the last decade, the test meal has been standardized, and the normal 6 h cumulative 13 C recovery rate is approximately 27-29 % [24,25]. Although age and gender do not influence the test results, even moderate exercise can increase or decrease the results [26,27].…”

Guidelines for the investigation of chronic diarrhoea in adults: British Society of Gastroenterology, 3rd edition

“…Equally, while European guidelines have recommended the use of the C13 mixed triglyceride breath test as an alternative to faecal elastase testing, it is not widely available with poor sensitivity in mild/moderate disease 204 and therefore not recommended.…”

Challenges in the management of pancreatic exocrine insufficiency

“…The length of time over which excreted CO 2 is measured, the constituents of the test-meal, and physical exercise may affect results[ 14 ]. An attempt to simplify the 13 C-MTG breath test showed that when cumulative CO 2 excretion is measured over less than 4 h the test loses its specificity, although it remains highly sensitive[ 15 ]. The test may generate false positives in patients with steatorrhoea of non-pancreatic origin, such as those with severe duodenal mucosal disease[ 16 ].…”