title: Quantitative assessment of total body stores of vitamin A in adults with the use of a 3-d deuterated-retinol-dilution procedure.
abstract: BACKGROUND
  The conventional deuterated-retinol-dilution (DRD) technique provides a quantitative estimate of total body stores of vitamin A in humans. The procedure requires equilibration of serum deuterated retinol with nondeuterated retinol after administration of an oral dose of deuterated vitamin A. Equilibration takes approximately 3 wk to complete.
  
  
  OBJECTIVE
  Our goal was to develop a predictive mathematical formula for quantitative assessment of total body stores of vitamin A in adults by using a procedure that takes less time to perform because serum isotope equilibration is not required, so that blood drawing can be done 3 d, instead of approximately 3 wk, after isotope dosing.
  
  
  METHODS
  Ratios of serum deuterated to nondeuterated retinol (D:H retinol) were determined in Filipino adults (n = 68) 3 and 20 d after an oral dose of 0.015 mmol [(2)H(4)]retinyl acetate and in Guatemalan adults (n = 15) 3 and 21 d after a 0.030-mmol dose. D:H retinol values 20 or 21 d after the isotope dose were used in a mathematical formula to obtain quantitative estimates of total body stores of vitamin A that were then correlated with serum D:H retinol values 3 d after the isotope dose.
  
  
  RESULTS
  The relation between these variables was nonlinear and was described by the following equation: total body stores of vitamin A (in mmol retinol) = 0.00468 x 10(37(isotope dose in mmol))/D:H retinol in serum 3 d after the isotope dose.
  
  
  CONCLUSIONS
  A 3-d DRD technique could be used for quantitative assessment of total body stores of vitamin A; this technique takes less time than does the conventional DRD technique.
authors.affiliation: Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, Boston, MA 02111, USA. judy.ribaya-mercado.tufts.edu
authors.forename: Judy D
authors.initials: JD
authors.lastname: Ribaya-Mercado
authors.forename: Florentino S
authors.initials: FS
authors.lastname: Solon
authors.forename: Gerard E
authors.initials: GE
authors.lastname: Dallal
authors.forename: Noel W
authors.initials: NW
authors.lastname: Solomons
authors.forename: Liza S
authors.initials: LS
authors.lastname: Fermin
authors.forename: Manolo
authors.initials: M
authors.lastname: Mazariegos
authors.forename: Gregory G
authors.initials: GG
authors.lastname: Dolnikowski
authors.forename: Robert M
authors.initials: RM
authors.lastname: Russell
mesh_terms: D000284:Administration, Oral; D000368:Aged; D000369:Aged, 80 and over; D003903:Deuterium; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007201:Indicator Dilution Techniques; D008297:Male; D008433:Mathematics; D008875:Middle Aged; D009752:Nutritional Status; D010679:Philippines; D013997:Time Factors; D014801:Vitamin A / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism*
chemical_list: D014801:Vitamin A; D003903:Deuterium