Measuring Total Body Water and Fluid Volume Homeostasis
Metabolic Solutions offers administration kits, project design assistance and a mass spectrometry service to help researchers determine total body water using deuterium oxide (D2O) and oxygen-18 stable isotope methods in clinical protocols. We are a one-stop service to implement the measurement of total body water in your protocols.
The total body water technique is useful for monitoring:
- Changes in fluid status after drug administration (ex. Pioglitazone)
- Drug distribution in individuals with decreased total body water
- Changes in body composition under various physical states, such as illness, exercise, or dehydration
Total body water (body composition) has been measured using stable isotopes of oxygen (oxygen-18) and deuterium (deuterium oxide, D2O) for more than 40 years. The principle is based on the theory that water is distributed in all parts of the body except body fat. Most researchers chose deuterium oxide to estimate total body water due to the lower cost of isotope. The 4% overestimation of total body water by the technique can be corrected in the final calculations. Oxygen-18 water is frequently used to measure total body water when another deuterium labeled tracer (ex. 6,6-D2-glucose) is co-administered in an experiment.
| Body Fluid Compartments (70 kg male) | |||
|---|---|---|---|
| % of Body Weight | % of Total Body Water | Volume (Liters) | |
| ECF | 27 | 45 | 19 |
| Plasma | 4.5 | 7.5 | 3.2 |
| ISF | 12.0 | 20.0 | 8.4 |
| Dense CT water | 4.5 | 7.5 | 3.2 |
| Bone water | 4.5 | 7.5 | 3.2 |
| Transcellular | 1.5 | 2.5 | 1.0 |
| ICF | 33 | 55 | 23 |
| TBW | 60% | 100% | 42 liters |
Alterations of body composition can often reveal adequacy of nutritional support and the presence or progression of disease. Total body water is commonly used to determine body composition but is further divided into independently varying compartments, intracellular water and extracellular water. If sodium bromide is co-administered with oxygen or deuterium-labeled water, the extracellular water space can be determined. Variations in extracellular water can occur due to poor nutrition, growth or disease and may not effect changes in total body water.
Extracellular Water Determination
Metabolic Solutions offers project design assistance and an analytical service to provide direct measurement of extracellular water using sodium bromide (NaBr) dilution space. Knowledge of extracellular water provides a more complete understanding of body composition as it relates to nutritional and health status.
Unlike most methods that employ radiolabels or require expensive instrumentation, bromide offers a safe, inexpensive, and accurate means to determine extracellular water. Estimates of extracellular water using bromide dilution space are easily adapted to determinations in human infants, experimental animals, field studies, and applications involving patients receiving critical care.
Bromide estimations of extracellular water do not alter body composition and can be easily incorporated into existing studies. For example, extracellular water and bromide sampling protocols are compatible with the oxygen-18 or deuterium oxide total body water technique.
If you need protocol information on how to conduct total body water tracer studies, the following technical paper is available: Total Body Water Determination
Published Total Body Water (Body Composition) Studies Analyzed By Metabolic Solutions
- Andrews, F.M., Nadeau, J.A., Saabye, L., Saxton, A.M. Measurement of total body water in horses using deuterium oxide dilution. Am J Vet Res 58(10):1060-1064, 1997.
"Deuterium oxide appears safe and efficacious for determining total body water content in horses and may be helpful for determining changes in total body water content during exercise and disease." - Armstrong, L.E., Kenefick, R.W., Castellani, J.W., Riebe, D., Kavouras, S.A., Kuznicki, J.T., Maresh, C.M., Bioimpedance spectroscopy technique: intra-, extracellular, and total body water., Medicine & Science in Sports and Excerise, 29(12):1657-1663, 1997.
"The purpose of this study was to test the validity of a multiple frequency bioimpedance spectroscopy (BIS) technique that estimates extracellular fluid volume (ECV), intracellular fluid volume (ICV), and total body water (TBW)." - Cincotta, A.H., MacEachern, T.A., Meier, A.H. Bromocriptine redirects metabolism and prevents seasonal onset of obese hyperinsulinemic state in Syrian hamsters. Am. J. Physiol. 264(27):E285-E293, 1993.
"Metabolic and hormonal effects of bromocriptine were studied in seasonally obese female Syrian hamsters."
