C-13 sodium octanoate breath test

In the differential diagnostics of functional dyspepsia, reflux disease and for the indication of some modern drugs (prokinetics) the speed of emptying the stomach and motility can be used to measured by a non-radioactive and non-invasive breath test. The 13 C-octanoic acid (caprylic acid) breath test is a non-invasive gastric evacuation test.

Octanoic acid is not absorbed in the stomach, but is relatively quickly absorbed by the duodenal mucosa. The liver then produces 13 CO2, which is determined in exhaled air.

Examination of the gastric passage by a 13 C-octanoate breath test shows a high correlation with the scintigraphic method. The 13 C-octanoic acid breath test determines the amount of food that passes into the duodenum, while scintigraphy determines the amount of food that remains in the stomach. Another variantion is a13 C-acetate breath test.

Implementation
The testing breakfast can be solid (poached egg with 3 g of oil, toast - 40 g and butter 10 g) or semi-solid (200 g of milk, chocolate pudding). 100 mg of sodium 13 C-octanoic acid is added to the testing breakfast. The sampling of the exhaled air is performed continuously for 4 hours. The evaluation of the process kinetics by measuring the change in the ratio of 13 CO 2  : 12 CO 2 can be performed by IRMS or IR analyzers.

The normal range is 110-160 minutes for a solid diet and 91-155 minutes for a semi-solid diet.