Adjusting ferritin concentrations for inflammation: Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project

• Authors: Sorrel ML Namaste, Strengthening Partnerships, Results, and Innovations in Nutrition Globally; Fabian Rohner, GroundWork; Jin Huang, Johns Hopkins University; Nivedita L Bhushan, University of North Carolina Chapel Hill; Rafael Flores-Ayala, Centers for Disease Control and Prevention; Roland Kupka, UNICEF; Zuguo Mei, Centers for Disease Control and Prevention; Rahul Rawat, International Food Policy Research Institute; Anne Williams, Emory University; Daniel J Raiten, Eunice Kennedy Shriver Natl Inst Child Hlth & Hum; Christine A Northrop-Clewes, Independent Public Health Nutrition Consultant; Parminder Suchdev, Emory University
• Journal Title: American Journal of Clinical Nutrition
• Volume: Volume 106, Number 1
• Publisher: American Society for Nutrition | 2017-06-14, Pages 359S-371S
• Type of Work: Article | Final Publisher PDF
• Subjects: Health Sciences, Nutrition; Health Sciences, Public Health
• Keywords: Science & Technology; Life Sciences & Biomedicine; Nutrition & Dietetics; anemia; ferritin; inflammation; iron deficiency; meta-analysis; nutritional assessment; ACUTE-PHASE RESPONSE; PLASMODIUM-FALCIPARUM INFECTION; SOLUBLE TRANSFERRIN RECEPTOR; NECROSIS-FACTOR-ALPHA; IRON STATUS; VITAMIN-A; MALARIA; CHILDREN; ERYTHROPOIETIN; HOMEOSTASIS

Abstract

Background: The accurate estimation of iron deficiency is important in planning and implementing interventions. Ferritin is recommended as the primary measure of iron status, but interpretability is challenging in settings with infection and inflammation. Objective: We assessed the relation between ferritin concentrations and inflammation and malaria in preschool children (PS C) (age range: 6-59 mo) and women of reproductive age (WRA) (age range: 15-49 y) and investigated adjustment algorithms to account for these effects. Design: Cross-sectional data from 15 surveys for PSC (n = 27,865) and 8 surveys for WRA (24,844), from the Biomarkers Reflecting the Inflammation and Nutritional Determinants of Anemia (BRINDA) project were analyzed individually and combined with the use of a meta-analysis. Several approaches were explored to estimate depleted iron stores (ferritin concentration < 12 μg/L in PSC and < 15 μg/L in WRA) in inflammation and malaria settings as follows: 1) increase ferritin-concentration cutoff to < 30 μg/L; 2) exclude individuals with C-reactive protein (CRP) concentrations > 5 mg/L or α-1-acid glycoprotein (AGP) concentrations > 1 g/L; 3) apply arithmetic correction factors; and 4) use a regression correction approach. Results: Depleted iron-store estimates incrementally increased as CRP and AGP deciles decreased (4% compared with 30%, and 6% compared with 29% from highest compared with lowest CRP deciles for pooled PSC and WRA, respectively, with similar results for AGP). Depending on the approach used to adjust for inflammation (CRP plus AGP), the estimated prevalence of depleted iron stores increased by 7-25 and 2-8 absolute median percentage points for PSC and WRA, respectively, compared with unadjusted values. Adjustment for malaria in addition to CRP and AGP did not substantially change the estimated prevalence of depleted iron stores. Conclusions: Our results lend support for the use of internal regression correction to estimate the prevalence of depleted iron stores in regions with inflammation. This approach appears to mathematically reflect the linear relation of ferritin concentrations with acute-phase proteins. More research is warranted to validate the proposed approaches, but this study contributes to the evidence base to guide decisions about how and when to adjust ferritin for inflammation.