Single-point gastric emptying breath tests

A breath test method for identifying delayed gastric emptying, comprising:

• supplying a subject with a solid breath test meal having a Spirulina platensis 13C label, wherein the solid breath test meal has a caloric content of between about 200 and about 400 kilocalories;
• collecting a post-meal breath sample of the subject, wherein the collecting the post-meal breath sample consists of collecting only a single breath sample of the subject at only a single 90 minute time point after the subject consumes the solid breath test meal;
• providing a device configured to measure a ratio of 13CO2/12CO2 in the single breath sample;
• quantitatively measuring the ratio of 13CO2/12CO2 in the single breath sample using the device;
• generating a gastric emptying measurement from the single breath sample;
• and
• identifying whether the subject has delayed gastric emptying based on the gastric emptying measurement, wherein the step of identifying whether the subject has delayed gastric emptying involves classifying the subject based on a dichotomous classification system such that the subject is classified as having either normal gastric emptying or delayed gastric emptying.