13C-egg white breath test:: a non-invasive test of pancreatic trypsin activity in the small intestine

Background-The recent availability of egg white protein highly enriched with C-13 has allowed breath test technology to be adapted for the study of protein digestion and absorption. Pancreatic trypsin is considered to be the key enzyme in the proteolytic cascade. Aim-To evaluate trypsin activity in the small intestine of healthy volunteers and patients with pancreatic disease by a recently developed C-13-egg white breath test. Methods-A total of 48 healthy volunteers and 30 patients with pancreatic disease were studied after ingestion of a test meal consisting of 22 g C-13-labelled egg protein. Breath samples were taken before and after ingestion of the meal and analysed for (CO2)-C-13 concentration. Moreover, pancreatic trypsin output after maximal stimulation was measured in 13 patients and nine healthy volunteers. Results-The six hour cumulative (CO2)-C-13 excretion in breath was significantly lower in patients than controls (mean (SEM): 6.23 (0.82)% v 19.16 (0.58)%, p<0.0001). An excellent correlation was found between the six hour cumulative (CO2)-C-13 excretion and trypsin activity after maximal pancreatic stimulation. Conclusion-The non-invasive C-13-egg white breath test is promising as an indirect pancreatic proteolytic function test.