PEDIATRICS Vol. 121 No. 3 March 2008, pp. 652 (doi:10.1542/peds.2007-3713)
LETTER TO THE EDITOR |
Iron-Status Indicators: In Reply
Jane M. Brotanek, MD, MPHGlenn Flores, MD
Division of General Pediatrics
Department of Pediatrics
University of Texas Southwestern Medical Center and
Children's Medical Center Dallas
Dallas, TX 75390-9063
Michael Weitzman, MD
Department of Pediatrics
New York University School of Medicine
New York, NY 10016
We thank Cusick et al for their clarification regarding the Centers for Disease Control and Prevention (CDC) transition to a new model to assess iron deficiency in 1 to 2-year-old children, beginning with the 2003–2004 National Health and Nutrition Examination Survey (NHANES). At the time our analyses were performed,1 we did not have access to information on the CDC's decision to use this new approach for assessing iron deficiency, despite several calls and e-mails to staff at the National Center for Health Statistics and several visits to their Web site.
We commend the CDC for recognizing the importance of continuing to monitor iron deficiency among US infants and toddlers, a group at very high risk for iron deficiency and anemia. The ratio of serum transferrin receptor (sTfR) to serum ferritin (R/F ratio) has been shown to be a useful tool for estimating total body iron stores.2,3 Of concern, however, is that there does not seem to be enough evidence, consensus of expert opinion, and clinical acceptance of the R/F ratio to justify its use at this time in the NHANES to monitor iron deficiency in this high-risk group. A literature review and consultation with several prominent hematologists and iron experts across the country indicate that studies are urgently needed to standardize the R/F method.4–7 There is also some controversy about whether this new measure can be used to diagnose iron deficiency without anemia2,4 and iron deficiency in the presence of infection.5 Most importantly, more work is needed to validate the use of sTfR and establish age-specific reference ranges for this measure in children.3,6,8,9
In contrast, the ferritin model used in the NHANES III and NHANES IV (1999–2002) has been carefully described in scholarly work dating back to 1980, with laboratory cutoffs for all age groups in the US population established by an expert panel.10–12 We suggest that the NHANES reintroduce the ferritin model and resume collection of transferrin saturation and erythrocyte protoporphyrin in children aged 1 to 2 years, while keeping sTfR. This would allow tracking of iron deficiency in all US children using a well-founded method while providing valuable opportunities to study sTfR and correlations with established iron-status indicators. Before the R/F ratio can be used reliably to monitor iron deficiency in US infants and toddlers, there is a clear need for recommendations by expert scientific working groups and additional rigorous studies evaluating the R/F model and establishing definitive age-specific reference ranges in US children.
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PEDIATRICS (ISSN 1098-4275). ©2008 by the American Academy of Pediatrics
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