Doubly labeled water method

The doubly labeled water method is used to determine the moles of COi produced as follows. The human subject drinLs a known quantity of deuterated water ( HjOj and oxygen-18 labeled water Hydrogen-2 is deuterium. 

Schoeller, D. A., and Hnilicka, J. M. (1996). Reliability of the doubly labeled water method for the measurement of total daily enei v expenditure in frce living humans. /.. NFulr. 126, 348S-354S. 

SchoeKer, D. A., and Santen, E. (1982). Measurement of energy expenditure in humans by doubly labeled water method. /. Appl Physiol 53, 955-959. 

TOTAL ENERGY EXPENDITURE OF FREE-LIVING HUMANS CAN BE ESTIMATED WITH THE DOUBLY LABELED WATER METHOD... 

The doubly labeled water method ( H2 0) yields an average caloric expenditure for a period of 5-14 days. The procedure is noninvasive, nonre-strictive, and reflective of actual caloric expenditure under free-living conditions. 

Black, A. E., Prentice, A. M., and Coward, W. A. (1986). Use of food quotients to predict respiratory quotients for the doubly-labelled water method of measuring energy expenditure. Hum. Nutr. Clin. Nutr. 40C, 381-391. 

Schoeller, D. A., Leitch, C. A., and Brown, C. (1986). Doubly labeled water method in vivo oxygen and hydrogen isotope fraaionation. Am. J. Physiol. 1, R1137-R1143... 

Ballevre, O., G. Anantharaman-Barr, P. Gicqaello, C. Piquet-Welsh, A.-L. Thielin and E. Fern, 1994. Use of the doubly-labelled water method to assess energy expenditure in free living cats and dogs. J. Nutr. 124,2594S-2600S. 

The indirect calorimetry formulas require two measures to calculate EE and RQ. So the doubly labelled water method relies on some extra detections of the RQ, the oxygen consumption or, as usual, some assumptions on the mean RQ during the measurements. Besides the standard values provided from the IDECG, very satisfactory assumptions can be made by taking into account the food composition during the measuring period and changes in the fat content of the body [38]. 

Labelled bicarbonate on its own can be used to assess EE instead of doubly labelled water. This technique is valuable for short intervals of about 1-3 days because of the shorter biological half life of bicarbonate compared with water. It is applicable to humans only, if stable marked bicarbonate (NaH CO,) is used. This substance is less expensive than doubly labelled water, but relies like DLW on the quite expensive technology of IRMS. The bicarbonate is con.stant-ly infused and will reach rapidly an equilibrium with the CO2-P00I of the subject s body. COj-production will dilute this pool. The CO production rate can be calculated from the variations in the dilution of labelled COj and the infusion rate. The method assumes no isotope exchange or fixation and a constant pool of bicarbonate. It is not as accurate as the doubly labelled water method Elia [39] found individual accuracies of up to 6%, validated against whole body calorimetry in a calorimetric chamber. 

Some empirically interconnections have been found between locomotor activity and energy expenditure in free living subjects of a given lifestyle. But these connections are too weak to be used in calorimetric experiments. They are often used in balanced food intake experiments or studies performed utilising the doubly labelled water method. 

A.M. Prentice, (Ed.) The Doubly-Labelled Water Method for Measuring Energy Expenditure. Technical Recommendations for Use in Humans, ed. International Dietary Energy Consultancy GroupVienna IDECG/IAEA, NAHRES-4 1990. 

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