A Better Screening Test For Infant Iron Deficiency?

Iron deficiency is estimated to affect nearly 10 percent of Americanchildren one to two years of age. Early detection and treatment arecritical because iron deficiency can impair infant mental development,possibly permanently, even before it progresses to anemia (clinicallyidentified as a low hemoglobin level).

The study, done at Children's Hospital Boston, is the first tocompare the test, called CHr, with the standard hemoglobin test as ascreen for iron deficiency in infants. Hemoglobin is theiron-containing, oxygen-carrying molecule in red blood cells; the CHrtest measures the hemoglobin content of reticulocytes, or immature redblood cells, whereas the standard hemoglobin test is based on theentire population of red blood cells. Because reticulocytes are presentin the bloodstream for only 24 to 48 hours, as compared with severalmonths for mature red blood cells, measuring the reticulocytehemoglobin content (i.e., CHr) provides a more timely indication ofiron status, the investigators say.

In this study, 200 healthy infants 9 to 12 months of ageunderwent both tests, as well as a transferrin saturation test, whichis the "gold standard" test for iron deficiency but is impractical forroutine screening. Using the optimal CHr cutoff value (established as27.5 picograms), CHr correctly identified 83 percent of theiron-deficient infants, compared with only 26 percent identified by thecurrent screening standard (a hemoglobin level less than 11grams/deciliter).

"Our findings are important because, while iron deficiency canbe readily treated, practitioners haven't had a simple, reliable andpractical screening test to detect it early enough. Now they might,"said Henry Bernstein, DO, Associate Chief, General Pediatrics,Children's Hospital Boston and the principal investigator of the study."This study shows that CHr can be used to detect iron deficiencyearlier and more accurately than standard hemoglobin screening. Onceconfirmed in larger, multicenter studies, these findings could changeour preferred screening practices for the early detection of irondeficiency." He added that the CHr test is simple, requires no extratubes of blood to be drawn and involves no additional cost.

"There is mounting evidence that iron deficiency in infants cancause permanent neurocognitive deficits, even before it has progressedto the point of causing anemia," said lead investigator ChristinaUllrich, MD, a fellow in pediatric hematology and oncology atChildren's Hospital Boston and the Dana Farber Cancer Institute. "Theability of the CHr test to identify more infants, at an earlier stageof iron deficiency, makes it a better choice for screening than thecurrent hemoglobin test."

Iron deficiency is the most common nutritional deficiency inthe world. Infants and toddlers are especially susceptible because oftheir rapid growth, increased demands for iron, and variable dietaryintake. The deficiency progresses in three stages: 1) depletion of thebody's iron stores; 2) deficiency, in which hemoglobin synthesis isimpaired, resulting in a fall in CHr; and 3) anemia, in whichred-blood-cell hemoglobin is below normal for a person's age. Irondeficiency is usually readily treated with dietary ironsupplementation.

Under current guidelines, children are first screened with thehemoglobin test at nine to 12 months of age. However, iron deficiencycan exist for some time before causing anemia. There are other teststhat can diagnose iron deficiency in the absence of anemia, but theyare impractical for routine clinical screening. Thus, current screeningpractices miss iron deficiency in non-anemic infants in whom adverseconsequences may be developing.

Founded in 1869 as a 20-bed hospital for children, Children'sHospital Boston today is the nation's leading pediatric medical center,the largest provider of health care to Massachusetts children, and theprimary pediatric teaching hospital of Harvard Medical School. Inaddition to 347 pediatric and adolescent inpatient beds andcomprehensive outpatient programs, Children's houses the world'slargest research enterprise based at a pediatric medical center, whereits discoveries benefit both children and adults. More than 500scientists, including eight members of the National Academy ofSciences, nine members of the Institute of Medicine and 10 members ofthe Howard Hughes Medical Institute comprise Children's researchcommunity. For more information about the hospital visit: http://www.childrenshospital.org.