Effects of inflammation and Plasmodium falciparum infection on soluble transferrin receptor and plasma ferritin concentration in different age groups: a prospective longitudinal study in Côte d'Ivoire.

Background: Iron deficiency (ID) is a major cause of anemia, along with other nutritional, parasitic, and genetic factors. Accurate biomarkers are needed to estimate the relative contribution of ID to anemia. Soluble transferrin receptor (sTfR) is thought to be unaffected by inflammation.
Objectives: The objectives were to determine the difference in sTfR and plasma ferritin (PF) concentrations among infants (6-23 mo of age), school-age children (6-8 y of age), and women (15-25 y of age) with and without inflammation and with and without Plasmodium falciparum infection and to assess the effect of adjusting sTfR and PF for inflammation or for P. falciparum infection on the estimated prevalence of ID.
Design: The data were derived from a 14-mo prospective longitudinal survey on anemia, which was conducted in the Taabo area, south-central Côte d'Ivoire.
Results: At baseline, sTfR concentration was significantly higher in infants and school-age children with either inflammation or P. falciparum infection than in control individuals without inflammation or without P. falciparum infection. Individuals with inflammation had significantly higher PF concentrations than did subjects without inflammation. Adjustments in sTfR concentrations for inflammation or P. falciparum infection in infants and school-age children resulted in significantly lower ID prevalence. Adjustment of PF for inflammation and Plasmodium infection resulted in a higher ID prevalence in infants and women.
Conclusions: In Ivorian infants and school-age children, ID prevalence was considerably lower after adjustment of sTfR for inflammation. However, as the prevalence estimates for ID differed widely if based on sTfR or PF, caution is still needed when estimating ID prevalence in areas with a high prevalence of inflammation or malaria. This trial was registered at controlled-trials.com as ISRCTN02181959.