Objective: To assess the impact of the acute-phase response (APR) during inflammation on Fe, Zn and vitamin A biomarkers to allow accurate evaluation of micronutrient status in populations.
Design: Ferritin (FER), soluble transferrin receptor (TfR), retinol-binding protein (RBP), Zn, α1-acid glycoprotein and C-reactive protein concentrations were measured. Correction factors (CF) for each biomarker were calculated as the ratio for groups at different stages of inflammation v. the reference group without inflammation.Setting/SubjectsSenegalese (n 594) and Cambodian schoolchildren (n 2471); Cambodian women of reproductive age (n 2117).
Results: TfR was higher during the incubation phase (CF=1·17) and lower during early and late convalescence (CF=0·87 and 0·78). FER was higher during all phases (CF=0·83, 0·48 and 0·65, respectively). RBP was higher during incubation (CF=0·88) and lower during early convalescence (CF=1·21). No effect of inflammation on Zn status was found.
Conclusions: Inflammation led to overestimation of Fe status and underestimation of vitamin A status. The response of the biomarker for vitamin A status to inflammation depended on the vitamin A status of the populations. Surprisingly, the assessment of Zn status was hardly affected by inflammation. Different phases of the APR had opposite effects on the assessment of Fe status using TfR. More research is needed to define the correct methods to adjust for inflammation in nutritional studies.
Keywords: Ferritin; Inflammation; Retinol-binding protein; Soluble transferrin receptor; Zinc.