Background: The number of different laboratory tests and reference values are used to diagnose iron deficiency, but there is no agreement regarding the diagnostic criteria for infants. Aim of study. To establish reference values for serum ferritin, mean cell volume, and hemoglobin in infants aged from 9 to 12 months in Estonia and to evaluate the diagnostic characteristics of serum ferritin, mean cell volume, and hemoglobin in the diagnosis of iron deficiency.
Methods: Altogether 195 healthy infants aged 9-12 months participated in the study. They were randomly selected out of 300 families from seven different counties from all over Estonia. Serum ferritin, hemoglobin, soluble transferrin receptor (sTfR) levels and mean cell volume were measured. The best cut-off values for serum ferritin, mean cell volume, and hemoglobin to diagnose iron deficiency, defined by sTfR>2.45 mg/L (n=25), were determined by receiver operating characteristic curves.
Results: The mean and reference values (5th and 95th centiles) for ferritin was 24 microg/L (4-55), 73 fl (68-80) for mean cell volume, and 112 g/L (101-128) for hemoglobin. The best cut-off values to diagnose iron deficiency were <10.9 microg/L for serum ferritin (sensitivity of 83% and specificity of 80%), <71 fl for mean cell volume (86% and 83%, respectively), and <107 g/L for hemoglobin (67% and 87%, respectively). The sensitivity and specificity of serum ferritin and mean cell volume in the diagnosis of iron deficiency were better than those of hemoglobin.
Conclusion: For the diagnosis of iron deficiency in infants aged 9-12 months, the cut-off values of <10.9 microg/L and <71 fl should be used for serum ferritin and mean cell volume, respectively.