Triple isotope method and analyzer for total energy expenditure measurements

摘要

A method of measuring energy expenditure in a living subject comprises: (a) administering a specified dose of doubly-labeled water (2H218O) to a living subject; (b) obtaining samples at three or more times of body water from the living subject; (c) measuring 2H/1H, 17O/16O and 18O/16O ratios in each of the obtained samples using optical spectroscopy; and (d) determining (1) a combined value of flux of body water and exhaled carbon dioxide from a change in measured 18O/16O over time, (2) a value of flux of body water alone from a change in measured 2H/1H over time, and (3) a reference value of isotopic background fluctuation from a change in measured 17O/16O over time. Using 17O measurements to estimate background fluctuations of the 2H and 18O decreases the required isotope dosing of subjects or decreases uncertainty at current dosing levels.

主权项

1. A method of measuring energy expenditure in a living subject, comprising:
administering a specified dose of doubly-labeled water (2H218O) to a living subject; obtaining samples at three or more times of body water from the living subject; measuring 2H/1H, 17O/16O and 18O/16O ratios in each of the obtained samples using optical spectroscopy; and determining (1) a combined value of flux of body water and exhaled carbon dioxide from a change in measured 18O/16O over time, (2) a value of flux of body water alone from a change in measured 2H/1H over time, and (3) a reference value of isotopic background fluctuation from a change in measured 17O/16O over time, wherein the specified dose is selected to be a low-enrichment dose that produces an initial δ(18O) enrichment in the body water of the subject of +20‰ relative to VSMOW.