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Modification of a 3‐d deuterated‐retinol dilution (DRD) equation for estimation of vitamin A (VA) stores in humans
Author(s) -
Duca Frank Anthony,
Green Michael H
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.716.5
Subject(s) - chemistry , structural equation modeling , endocrinology , isotope dilution , vitamin , medicine , mathematics , chromatography , statistics , mass spectrometry
Isotope dilution analysis has been successfully used to estimate vitamin A stores in humans via the Furr‐Olson DRD equation: estimated total body stores = F × dose × { S × a × [(1/D:H) −1]} (Am J Clin Nutr 1989; 49 :713). The method requires a blood sample 21 d after isotope administration and involves several assumptions (factors F , S and a ). Using VA tracer data from rat and human studies, we refined a modified DRD equation (J Nutr 2008; 138 :971) that uses a 3‐d sample, a time that is more feasible in the field. We found that the VA specific activity ratio in plasma vs. stores (factor S in DRD equation) varies with VA status in both rats and humans. Also, the amount of tracer irreversibly lost between dose administration and blood sampling (factor a ) increases as status decreases. In contrast, retention (factor F ) increases as status increases. Applying these findings to the original DRD equation, we developed a new equation in which S, F, and a vary with a subject's 3‐d plasma VA deuterium:hydrogen (D:H) ratio. For data from humans of varying age, gender and ethnicity, VA stores predicted by the new equation agree better with estimates from the original 21‐d Furr‐Olson equation than do values obtained using other published 3‐d DRD equations. Thus the new equation provides an improved tool to determine VA stores in humans. Funded by the College of Health and Human Development, Penn State Grant Funding Source : The College of Health and Human Development