Infant iron deficiency can permanently impair cognitive development even before it progresses to a low hemoglobin level or anemia. Researchers at Children's Hospital Boston have found that a simple alternative screening test, called CHr, detects iron deficiency earlier and more accurately than the hemoglobin test used currently. Their study appeared in the August 24/31 JAMA.
The CHr test has been available since 1993, but has been used in limited settings, such as hemodialysis patients. Hank Bernstein, DO, former associate chief of General Pediatrics at Children's (now at Dartmouth Medical School) and Hematology/Oncology fellow Christina Ullrich, MD, compared CHr with the standard hemoglobin test in 200 healthy babies 9 to 12 months old. Using the transferrin saturation test as the gold standard, CHr correctly identified 83 percent of iron-deficient infants, while the current hemoglobin test (with the standard cutoff of 11 g/dl) identified just 26 percent.
The CHr test measures the hemoglobin content of reticulocytes, or immature red blood cells, while the current hemoglobin test is based on the entire red-cell population. Because reticulocytes circulate for only one to two days, compared with several months for mature red cells, their hemoglobin content is a timelier indicator of iron status, the researchers say.
