Total Body Water

Metabolic Solutions offers administration kits, project design assistance and stable isotope analysis to help researchers determine total body water and fluid volume homeostasis using deuterium oxide (D2O) and oxygen-18 stable isotope methods. We offer sensitive methods for measuring deuterium and oxygen-18 levels in plasma, urine or saliva with as little as 15-25 µl of sample.

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 50 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 (70kg male)

 Compartment % of Body Weight % Total Body Water Volume (liters)
 ECF  27 45  19
 Plasma 4.5 7.5 3.2
 ISF 12 20 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
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 affect changes in total body water.

Extracellular Water Determination

Metabolic Solutions offers 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 with Stable Isotope Analysis Performed By Metabolic Solutions

  1. Moon JR, Stout JR, Smith AE, Tobkin SE, Lockwood CM, Kendall KL, Graef JL, Fukuda DH, Costa PB, Stock MS, Young KC, Tucker PS, Kim E, Herda TJ, Walter AA, Ferguson SL, Sherk VD, and Cramer JT. Reproducibility and validity of bioimpedance spectroscopy for tracking changes in total body water: Implications for repeated measurements. Br J Nutr 104(9):1384-94, 2010.
    “Comparison of bioimpediance spectroscopy to monitor total body water changes versus the deuterium oxide method.”
  2. Dalbo VJ, Roberts MD, Hassell SE, Moon JR, and Kerksick CM. Effects of a mineral antioxidant complex on clinical safety, body water, lactate response, and aerobic performance in response to exhaustive exercise. Int J Sport Nutr Exerc Metab. 20(5):381-92, 2010.
    “Investigated the safety and efficacy of a silica-based mineral antioxidant complex on total body water. This study used deuterium oxide and sodium bromide to determine total body water, intracellular water and extracellular water.”
  3. Moon JR, Smith AE, Tobkin SE, Lockwood CM, Kendall KL, Graef JL, Roberts MD, Dalbo VJ, Kerksick CM, Cramer JT, Beck TW, Stout JR. Clin Nutr. 28(5):516-25, 2009.
    “Evaluated bioimpediance spectroscopy for the estimation of total body water with isotope dilution techniques.”
  4. Andrews FM, Nadeau JA, Saabye L, and Saxton AM. 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.”
  5. Armstrong LE, Kenefick RW, Castellani JW, Riebe D, Kavouras SA, Kuznicki JT, and Maresh CM, 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).”