Abstract: A non-invasive method for the functional assessment of an inherited metabolic disorder in infants and children including administering to the patient a predetermined substrate labeled with a stable non-radioactive isotope of carbon .sup.13 C, analyzing the breath samples for the isotopic abundance of .sup.13 CO.sub.2, and calculating the quantity of substrate oxidized for determining the rate of substrate oxidation.

Abstract: A drink adapted to be consumed by a patient to enable measurement of gastric emptying of the liquid phase, is a fruit juice having mixed and suspended therein a quantity of Spirulina platensis alga grown in a .sup.13 CO.sub.2 atmosphere. These single cell organisms pass from the stomach into the small intestine where they are digested, absorbed and oxidized to produce a detectible rise in the level of .sup.13 CO.sub.2 in the patient's breath which is sampled and the measured valves plotted to enable determination of gastric emptying rate abnormalities.

Abstract: A biscuit adapted to be ingested by a patient to enable measurement of gastric emptying has added prior to baking Spirulina Platensis alga grown in a .sup.13 CO.sub.2 atmosphere. These single cell organisms are oxidized after digestion in the small intestine to produce a detectible rise in level of .sup.13 CO.sub.2 in the patient's breath which is sampled and plotted to enable diagnosis of abnormal gastric emptying rates.

Abstract: A measurement test for gastrointestinal transit time, including the steps of administering a dose of labeled glycosyl ureide, measuring the labeled CO.sub.2 and determining the amount of CO.sub.2 over time is described. The assay can be used for measuring the effectiveness of drugs, the effect of drugs on gastrointestinal motility diagnoses of gastrointestinal motility disease measuring the effectiveness of treatment, and the effect of diet on motility.

Abstract: In accordance with illustrative embodiments of the present invention as disclosed herein, a breath sample collecting device includes a flexible plastic bag having a mouthpiece and inlet valve assembly connected adjacent one end of the bag, and a sample transfer assembly connected adjacent the other end of the bag. The transfer assembly has a sleeve attached to a neck on the bag, such sleeve having an inner end wall which mounts a hollow needle having a sharp tip on its outer end in a manner such that the tip is within the bore of the sleeve to prevent accidental stick injuries. A rubber boot which closes the tip, and an elastomer stopper on an associated transfer device, are selectively pierced by the needle tip in response to compressive force to permit transfer of a breath sample from the bag to such associated device.