Reproducibility of two ¹³CO₂ breath tests dedicated to assess pancreatic exocrine function.

The aim of this study was to check on the reproducibility of two breath tests intended to test the pancreatic exocrine function accomplished with (13)C-mixed triglyceride ((13)C-MTG) or cornflakes naturally enriched in (13)C ((13)C-CF). The (13)CO₂ content within breath samples was determined with isotope-selective non-dispersive infrared spectrometry. A 72-h monitoring performed in healthy subjects revealed that a statistically significant rise in breath (13)CO₂ occurs between the 1st and the 9th hour and between the 1st and the 24th hour after intake of a test meal containing 300 mg (13)C-MTG (n=10) or 100 g (13)C-CF (n=12), respectively. In another two groups of 12 healthy volunteers each, short-term reproducibility of the two tests was assessed with paired examinations taken at a median interval of two days, whereas paired examinations separated by a median of 20 days served for the medium-term reproducibility assessment. In the case of either test, the medium-term reproducibility was not any worse than the short-term one. The reproducibility of the (13)C-CF breath test tended to be slightly worse than that of the (13)C-MTG breath test: a least detectable difference in 6-h cumulative (13)C breath excretion (which is expressed as the percentage of the administered dose of the substrate) amounted to 2.7 and 4.4 % (short-term reproducibility) and to 3.5 and 4.4 % (medium-term reproducibility) in the case of the (13)C-MTG breath test and the (13)C-CF breath test, respectively. It is concluded that both tests offer a satisfactory reproducibility for use within a clinical setting. In case the lipolytic and the amylolytic activity would be required to be examined in the same patient, the (13)C-CF breath test can be executed on the next day following the (13)C-MTG breath test, whereas reciprocally, a 1-day break is recommended before accomplishment of a (13)C-MTG breath test following a (13)C-CF breath test.