EVALUATION STUDIES OF THE C-13-MIXED TRIGLYCERIDE BREATH TEST IN HEALTHY CONTROLS AND ADULT CYSTIC-FIBROSIS PATIENTS WITH EXOCRINE PANCREATIC INSUFFICIENCY

The C-13-mixed triglyceride (C-13-MTG) breath test (BT) is a safe and noninvasive method to measure exocrine pancreatic function. We examine d the reproducibility of the C-13-MTG BT in a group of 17 healthy cont rols and 8 adult patients with cystic fibrosis (CF). In controls no st atistically significant difference in percentage dose recovered (PDR) was found between the first and the second result of repeated tests: t he mean values were 35.5 +/- 5.5 vs. 32.3 +/- 7.4 PDR (n = 17). Also i n the group of CF patients (n = 8) no significant difference between d uplicate tests was found: mean values 17.5 +/- 7.5 and 17.5 +/- 7.8 PD R, respectively. The coefficient of repeatability is 8 PDR for the con trols and CF patients together. Two factors might influence the outcom e of the test. First, individually measured CO2 excretion instead of t he usually assumed 9 mmol/h/kg CO2 production might alter the result o f the (CO2)-C-13-MTG BT. Therefore CO2 production was measured by indi rect calorimetry in 12 healthy controls and 13 CF patients. Measured C O2 excretion was not significantly different between healthy controls and CF patients. Secondly, exercise might influence BT results due to its separate effects on both CO2 production and excretion. The influen ce of physical exercise at a level of 25 or 50 W was studied on a bicy cle ergometer in 4 healthy controls during the last 5 min of each 30-m in sampling period. Exercise gave lower test results, on average 85% o f the PDR value at rest. Incidently, it was observed in 1 patient that use of C-13-enriched food during the day preceding the test caused in appropriately low test results in the C-13-MTG BT. The C-13-MTG BT is a test with a fair but less than desirable reproducibility. Test condi tions should be standardized to eliminate confounding influences. Exer cise should be limited or strictly defined. Diet on the day preceding the test should not contain naturally C-13-enriched food. There is no need to measure individual CO2 production.