Currently I am using the formula by Tam et al 2011.,
TBW = [((T x A/a) x ((Ea – Et)/(Es-Ep)))/1000]/1.04,
where A is the amount of dose solution drunk (g); a, amount of dose solution diluted in T (g); T, amount of water in which ‘‘a’’ was diluted in (g); Ea, enrichment of diluted dose; Et, enrichment of water used to dilute the dose; Ep, enrichment of baseline sample; Es, enrichment of postdose sample; 1.04, correction factor for overestimation of TBW by the use of D2O.
As the doubly labelled water solution that I've used came in a pre-mixed drinkable solution, I'm unsure about the values to substitute for 'T' as well as 'a'.
Hi Dr Waite,
Thank you so much for your answer!
I have managed to find out the concentration of the pre-mixed solution from the manufacturer so I guess I would be able to recalculate the total body water values.
Cheers,
Jiaxin
Hi Dr Andreas Jenet,
Thank you for the references!
I will definitely take a look at it.
Regards,
Jia Xin
check Body Composition Analysis of Animals A Handbook of Non-Destructive Methods
EDITOR: John R. Speakman. Cambridge University Press. 2008.
Yeah, I agree with Prof Cruz-neto and White, just reach for the Bible:
Speakman, J. R. (1997). Doubly labelled water: theory and practice. London: Chapman & Hall.
It's a tough read, but it will have all the equations and permutations that you need.
I also found that Nagy and Costa was a good entry point to the Speakman (1997) book. Speakman can be a bit dense, but Nagy and Costa's work is a little more intuitive for a first read:
Nagy, K. A. and Costa, D. P. (1980). Water flux in animals: analysis of potential errors in the tritiated water method. American Journal of Physiology Regulatory Integrative Comparative Physiology 238, R454-R465.
Hope this helps, although it sounds like you might be onto it annyway
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