MEASURING TOTAL BODY WATER (TBW) FOR BODY COMPOSITION ASSESSMENT BY DEUTERIUM OXIDE DILUTION TECHNIQUE Grace K. Munthali 1 & Nadine M. Coulibaly 2 1 National Institute for Scientific and Industrial Research, Lusaka - Zambia 2 Institut de Recherche en Sciences de la santé, Bobo-Dioulasso - Burkina Faso 1. INTRODUCTION • Stable isotope techniques have been used in studies of human nutrition for over 50 years. • Deuterium oxide (D 2 O or 2 H 2 O) is given orally and after mixing with body water is eliminated from the body in urine, saliva, sweat and human milk. • D 2 O is metabolised in the body in the same way as water, and is dispersed through the body water within a matter of hours. • Body water can be sampled in the form of saliva, urine, plasma or human milk and the enrichment of deuterium can be measured by isotope ratio mass spectrometry (IRMS) or Fourier transform infrared spectrometry (FTIR). 2. DEUTERIUM OXIDE DOSE PREPARATION Weigh the labelled dose bottle plus lid. Record the weight Add D 2 O to the dose bottle using a measuring cylinder, replace lid. Weigh the bottle plus D 2 O Record the exact weight of D 2 O in each dose Doses should be prepared in a food preparation area, not a laboratory 3. SALIVA SAMPLING AND DOSING 4. TOTAL BODY WATER (TBW) ANALYSIS Ask participant to empty bladder Weigh participant in light clothing (to 0.1 kg) Collect baseline saliva sample Participant drinks the dose of D 2 O. Add 50 ml drinking water to the bottle and ask the participant to consume this. Add another 50 ml drinking water and ask them to drink this also Collect first post dose saliva sample Wait for a further 1 hour Collect second post dose saliva sample International Symposium on MAM, 26-29 May 2014, IAEA HQ, Vienna, Austria Wait for the dose to equilibrate with body water (3-4 hours) Invert dose bottle to ensure contents are fully mixed Typical FTIR Instrument Analyse saliva samples using FTIR 5. CALCULATIONS TBW (kg) = V D / 1.041 FFM (kg) = TBW (kg) / Hydration factor FM (kg) = body weight (kg) – FFM (kg) FM=Fat mass FFM=Fat-free mass V D =Volume of distribution 6. REFERENCES (i) International Atomic Energy Agency (IAEA): Assessment of Body Composition and Total Energy Expenditure in Humans Using Stable Isotope Techniques. IAEA Human Health Series 3. Vienna: IAEA; 2009. (ii) International Atomic Energy Agency (IAEA): Introduction to Body Composition Assessment Using the Deuterium Dilution Technique with Analysis of Saliva Samples by Fourier Transform Infrared Spectrometry. IAEA Human Health Series 12. Vienna: IAEA; 2010 (iii) International Atomic Energy Agency (IAEA): Introduction to Body Composition Assessment Using the Deuterium Dilution Technique with Analysis of Urine Samples by Isotope Ratio Mass Spectrometry. IAEA Human Health Series 13. Vienna: IAEA; 2010

MEASURING TOTAL BODY WATER (TBW) FOR … · measuring total body water (tbw) for body . composition assessment by deuterium oxide dilution technique. grace k. munthali1 & nadine m

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MEASURING TOTAL BODY WATER (TBW) FOR BODY COMPOSITION ASSESSMENT BY DEUTERIUM OXIDE DILUTION

TECHNIQUE

Grace K. Munthali1 & Nadine M. Coulibaly2 1National Institute for Scientific and Industrial Research, Lusaka - Zambia

2Institut de Recherche en Sciences de la santé, Bobo-Dioulasso - Burkina Faso

1. INTRODUCTION • Stable isotope techniques have been used in

studies of human nutrition for over 50 years. • Deuterium oxide (D2O or 2H2O) is given orally

and after mixing with body water is eliminated from the body in urine, saliva, sweat and human milk.

• D2O is metabolised in the body in the same way as water, and is dispersed through the body water within a matter of hours.

• Body water can be sampled in the form of saliva, urine, plasma or human milk and the enrichment of deuterium can be measured by isotope ratio mass spectrometry (IRMS) or Fourier transform infrared spectrometry (FTIR).

2. DEUTERIUM OXIDE DOSE PREPARATION

Weigh the labelled dose bottle plus lid. Record the weight

Add D2O to the dose bottle using a measuring cylinder, replace lid. Weigh the bottle plus D2O

Record the exact weight of D2O in each dose

Doses should be prepared in a food preparation area, not a laboratory

3. SALIVA SAMPLING AND DOSING

4. TOTAL BODY WATER (TBW) ANALYSIS

Ask participant to empty bladder

Weigh participant in light clothing (to 0.1 kg)

Collect baseline saliva sample

Participant drinks the dose of D2O. Add 50 ml drinking water to the bottle and ask the participant to consume this. Add another 50 ml drinking water and ask them to drink this also

Collect first post dose saliva sample Wait for a

further 1 hour

Collect second post dose saliva sample

International Symposium on MAM, 26-29 May 2014, IAEA HQ, Vienna, Austria

Wait for the dose to equilibrate with body water (3-4 hours)

Invert dose bottle to ensure contents are fully mixed

Typical FTIR Instrument

Analyse saliva samples using FTIR

5. CALCULATIONS TBW (kg) = VD / 1.041 FFM (kg) = TBW (kg) / Hydration factor FM (kg) = body weight (kg) – FFM (kg) FM=Fat mass FFM=Fat-free mass VD=Volume of distribution

6. REFERENCES (i) International Atomic Energy Agency (IAEA): Assessment of Body Composition and Total Energy Expenditure in Humans Using Stable Isotope Techniques. IAEA Human Health Series 3. Vienna: IAEA; 2009. (ii) International Atomic Energy Agency (IAEA): Introduction to Body Composition Assessment Using the Deuterium Dilution Technique with Analysis of Saliva Samples by Fourier Transform Infrared Spectrometry. IAEA Human Health Series 12. Vienna: IAEA; 2010 (iii) International Atomic Energy Agency (IAEA): Introduction to Body Composition Assessment Using the Deuterium Dilution Technique with Analysis of Urine Samples by Isotope Ratio Mass Spectrometry. IAEA Human Health Series 13. Vienna: IAEA; 2010