Comparison of indicators of iron deficiency in Kenyan children1–6
Published Date:Mar 28 2012
Source:Am J Clin Nutr. 95(5):1231-1237.
Pubmed Central ID:PMC4697948
Funding:CC999999/Intramural CDC HHS/United States
In the absence of a feasible, noninvasive gold standard, iron deficiency (ID) is best measured by the use of multiple indicators. However, the choice of an appropriate single iron biomarker to replace the multiple-criteria model for screening for ID at the population level continues to be debated.
We compared ID defined as ≥2 of 3 abnormal ferritin (<12 μg/L), soluble transferrin receptor (TfR; >8.3 mg/L), or zinc protoporphyrin (ZP; >80 μmol/mol) concentrations (ie, multiple-criteria model) with ID defined by abnormal concentrations of any of the independent candidate iron biomarkers (ferritin alone, TfR alone, or ZP alone) and TfR/ferritin index (ID, >500). Values either were adjusted for inflammation [as measured by C-reactive protein (>5 mg/L) and α1-acid glycoprotein (>1 g/L) before applying cutoffs for ID] or were unadjusted.
In this community-based cluster survey, capillary blood was obtained from 680 children (aged 6–35 mo) for measurement of iron status by using ferritin, TfR, and ZP.
On the basis of the multiple-criteria model, the mean (±SE) prevalence of ID was 61.9 ± 2.2%, whereas the prevalences based on abnormal ferritin, TfR, or ZP concentrations or an abnormal TfR/ferritin index were 26.9 ± 1.7%, 60.9 ± 2.2%, 82.8 ± 1.6%, and 43.1 ± 2.3%, respectively, for unadjusted values. The prevalences of ID were higher for adjusted values only for low ferritin and an elevated TfR/ferritin index compared with the unadjusted values. The κ statistics for agreement between the multiple-criteria model and the other iron indicators ranged from 0.35 to 0.88; TfR had the best agreement (κ = 0.88) with the multiple-criteria model. Positive predictive values of ID based on the other iron indicators in predicting ID based on the multiple-criteria model were highest for ferritin and TfR. Receiver operating characteristic curve analysis indicated that TfR (AUC = 0.94) was superior to the other indicators in diagnosing ID based on the multiple-criteria model (P < 0.001). The inflammation effect did not appear to alter these observations appreciably.
TfR better estimates the prevalence of ID in preschoolers than do ferritin, ZP, and the TfR/ferritin index on the basis of multiple indexes in a high inflammation, resource-poor setting. This trial was registered at clinicaltrials.gov as NCT101088958.
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