13 C mixed triglyceride breath testing using infrared spectrometry: comparison of two devices in early infancy

Background/Objectives: The 13 C mixed triglyceride (MTG) breath test has been proposed for the non-invasive assessment of fat digestion and absorption. To evaluate whether reference values for the adequacy of fat absorption, set in the non-dispersive infrared spectrometry (NDIRS) system software proposed for healthy children and adults using the 13 C MTG breath test, are also applicable to infants of <5 months of age. Subjects/Methods: 13 C MTG breath testing with the NDIRS technique was performed in 54 healthy infants <5 months of age (38 breast-fed, 16 formula-fed) and six infants diagnosed with cystic fibrosis (CF) using two NDIRS devices, IRIS and FANci2. Results: The IRIS results were slightly higher compared with those assessed by the FANci2 device. The minimum cutoff value for pancreatic sufficiency (PS) is set as a cumulative percentage dose of 13 C recovered (cPDR) after 5 h of 13.0%. Pancreatic function status of six CF infants, three with PS and three with pancreatic insufficiency (PI), according to the 72 h-faecal fat balance test could be correctly determined with the 13 C MTG breath test using two NDIRS techniques. However, if these reference values had been used to determine pancreatic function status in healthy infants, 26 out of 54 infants would have been misclassified as pancreatic insufficient. Conclusions: Although the 13 C MTG breath test with the MS technique has the potential to be a suitable assessment of fat absorption in infants, the technique of NDIRS appears too insensitive in an infant population group.