Reticulocyte Hemoglobin Content to Diagnose Iron Deficiency in Children

Abstract

CONTEXT: Early identification of iron deficiency in children is essential to prevent the damaging long-term consequences of this disease. However, it is not clear which indices should be included in a diagnostic panel for iron deficiency and iron deficiency anemia in children. OBJECTIVE: To develop an effective approach for the diagnosis of iron deficiency and iron deficiency anemia in young children. DESIGN AND SETTING: Retrospective laboratory analysis, carried out over 7 weeks in 1996, using blood samples ordered by pediatricians and sent to a large metropolitan hospital for analysis. PATIENTS: A total of 210 children (mean [SD] age, 2.9 [2.0] years; 120 were male) who had a lead screening test (complete blood cell count and plasma lead level) ordered by a primary care pediatrician. MAIN OUTCOME MEASURES: Levels of hemoglobin (Hb), iron, transferrin, transferrin saturation (Tfsat), ferritin, and circulating transferrin receptor and reticulocyte Hb content (CHr) among patients with and without iron deficiency, defined as Tfsat of less than 20%, and iron deficiency anemia, defined as Tfsat of less than 20% and Hb level of less than 110 g/L. RESULTS: Of the 210 subjects, 43 (20.5%) were iron deficient; 24 of these had iron deficiency anemia. Reticulocyte Hb content and Hb levels were the only significant predictors of iron deficiency (likelihood ratio test [LRT] = 15.96; P<.001 for CHr, and LRT = 6.59; P = .01 for Hb), and CHr was the only significant multivariate predictor of iron deficiency anemia (LRT = 30.43; P<.001). Plasma ferritin level had no predictive value (P = .97). Subjects with CHr of less than 26 pg (optimal cutoff value based on sensitivity/specificity analysis) had lower Hb level, mean corpuscular volume, mean corpuscular Hb level, serum iron level, and Tfsat, and increased red blood cell distribution width vs those with CHr of 26 pg or more (P<.001 for all). CONCLUSIONS: Reticulocyte Hb content level was the strongest predictor of iron deficiency and iron deficiency anemia in children. It holds promise as an alternative to biochemical iron studies in diagnosis.