Metabolic Solutions offers project design assistance and stable isotope analysis services to help researchers determine energy expenditure using the doubly labeled water stable isotope method. Stable isotopes of hydrogen (deuterium oxide) and oxygen (oxygen 18) are routinely used to measure energy expenditure in free-living humans or field metabolic studies in animals.
The doubly labeled water method is a form of indirect calorimetry that has been extensively validated in animals and humans. The method is completely safe, requires only periodic sampling of body fluids (plasma, urine, saliva), is non-restrictive, and is ideally suited for measurement of energy expenditure in free-living or hospitalized patients.
A typical energy expenditure study protocol using the doubly labeled water method starts with a baseline plasma, saliva or urine collection to determine pre-dose values for the hydrogen and oxygen isotopes. The subject is given a single oral bolus dose of heavy water (2H218O). Generally, adults are given a dose consisting of 0.15 g H218O/kg body weight and 0.06 g 2H2O/kg body weight. Children and neonates are given higher doses per kilogram due to their faster water turnover rates. Additional samples are collected 1 to 2 weeks later. We offer sensitive methods for measuring deuterium and oxygen-18 levels in plasma, urine or saliva with 15-25 µl of sample. If you are interested in small animal energy expenditure studies, please visit our latest advances.