Assessing Model Parameters for Applying the Retinol Isotope Dilution (RID) Method
Condition: Vitamin A Deficiency; Malaria; Inflammation
MeSH terms: Malaria; Night Blindness; Vitamin A Deficiency; Inflammation
Study type: Interventional

Summary: 
      For assessing body retinol pools in preschool children, it is recommended that a blood sample
      is taken 14-21 days after isotope dosing. During this period, dietary intake of vitamin A
      should be controlled. Shortening of this period as has been validated for adults would reduce
      the burden for the children as well as improve research efficiency. The aim is to validate a
      4-day protocol for assessing body retinol pools in preschool children by modelling data
      derived by retinol isotope dilution (RID) method. Venous blood samples will be collected of
      60 children 4 days after dosing of 0.4 mg 13C-labeled retinyl acetate. A second venous blood
      sample will be collected at 6, 8, 12 hrs; and 1, 2, 4, 7, 11, 16, 22 and 28 days after dosing
      in subgroups of 6 children, randomly divided over the 10 additional time points. Body retinol
      pools will be modelled, and the time point at which a parsimonious model applies (presumably
      at day 4) will be assessed.
    

Detailed description: 
      For assessing body retinol pools in preschool children, it is recommended that a blood sample
      is taken 14-21 days after isotope dosing. During this period, dietary intake of vitamin A
      should be controlled. Shortening of this period as has been validated for adults would reduce
      the burden for the children as well as improve research efficiency. The aim is to validate a
      4-day protocol for assessing body retinol pools in preschool children by modelling data
      derived by retinol isotope dilution (RID) method. A secondary aim is to compare body retinol
      pools between children with and without inflammation and to assess the effect of asymptomatic
      malaria on model parameters. Preschool children (n=60), 36-59 months of age, residing in
      Telemu, Osun State, Nigeria will be recruited for the study. The study design is an
      observational pre/post study, for which body retinol pools will be measured using the RID
      method. Venous blood samples will be collected of all children 4 days after dosing of 0.4 mg
      13C-labeled retinyl acetate. A second venous blood sample will be collected at 6, 8, 12 hrs;
      and 1, 2, 4, 7, 11, 16, 22 and 28 days after dosing in subgroups of 6 children, randomly
      divided over the 10 additional time points. Children presenting with asymptomatic malaria
      will be treated, and a convenience subsample (n=10) will undergo a second assessment of body
      retinol pools determined with a venous blood collection on day 4 post-dosing only. Body
      retinol pools will be modelled, and the time point at which a parsimonious model applies
      (presumably at day 4) will be assessed. Presence of asymptomatic malaria and markers of
      inflammation will be assessed in all children at all time points. Body retinol pools and
      model parameters between subgroups of children with and without asymptomatic malaria and/or
      inflammation will be compared. Pre/post comparisons of body retinol pool estimates will be
      done for the follow up subsample.
    

Intervention name(s): Retinol Isotope Dilution (RID)
Intervention type(s): Other
Intervention description(s): 13C-retinyl acetate will be administered to subjects in order to assess their body retinol pools
Intervention MeSH terms: Vitamin A
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Diagnostic
Keywords: Vitamin A status; Retinol Isotope Dilution; Nigeria; Preschool children; Malaria; Inflammation