"Mixed" triglyceride breath test: methodological problems and clinical applications

Laboratory assessment of pancreatic function is unpleasant for the patient and time-consuming for the investigator since it requires duodenal intubation and measurement of maximal pancreatic enzyme output by means of perfusion techniques. Non-invasive indirect tests such as bentiromide test, pancreolauryl test and faecal fat measurement have been introduced in clinical practice but their results depend on the collaboration of the patient in collecting urine or stool. Moreover, faecal fat reflects fat malabsorption but it is neither sensitive nor specific to evaluate exocrine pancreatic function. With the aim to determine whether steatorrhea is due to pancreatic insufficiency, several 14C- (or 13C) breath tests have been developed in which triolein, trioctanoin, tripalmitin, and cholesteryl-octanoate are used as marker substances. In 1989, G. Vantrappen and its group in Leuven developed a breath test in which a new substrate was used: the [1,3-distearyl, 2[carboxyl-13C]octanoyl glycerol] or 13C-"mixed"-triglyceride (MT). The "mixed triglyceride breath test" (MTBT) was shown to be an excellent test of exocrine pancreatic insufficiency when compared with the maximal lipase output after CCK-pancreozymin stimulation. Aim of this paper is to review the methodology of the MTBT and its actual and future applications in clinical practice.