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The purpose of this study was to evaluate the need for separate Hb screening criteria according to race by evaluating the Hb response to a therapeutic trial of iron in 1-yr-old infants. Among the 1128 infants who were screened, a significantly larger percentage of blacks (37%) than Caucasians (22%) had a Hb less than 11.5 g/dl. However, when these screen-positive infants were treated with oral iron for 3 months, the percentage who had a greater than or equal to g/dl response was similar in blacks (38%) and Caucasians (35%). Our results indicated that a slight but significant inherent tendency to lower Hb values among the black infants was counter-balanced by a substantially higher prevalence of iron deficiency anemia. These findings are in favor of using uniform Hb screening criteria in similar populations.

The purpose of this study was to determine the Hgb response to a therapeutic trial of iron in infants with anemia compared to those with low-normal hemoglobin values. Hgb was determined in 1.128 one-year-old infants. The 278 infants (25%) who had an Hgb less than 11.5 gm/dl were given a three-month oral course of ferrous sulfate (3 mg iron/kg/day); the regimen was satisfactorily completed by 188 infants. Of the 75 infants whose initial capillary Hgb was in the anemic range (Hgb less than 11.0 gm/dl), 45% had an increase in venous Hgb greater than or equal to 1.0 gm/dl. Of the 113 infants with initial capillary values in the low-normal range (11.0 to 11.4 gm/dl), 28% had greater than or equal to 1.0 gm/dl Hgb response. Despite the lower rate of response in the low-normal group, almost half of the infants with a greater than or equal to 1 gm/dl response would have been missed by using the generally accepted cutoff value of 11 gm/dl for a therapeutic trial. Because of the low cost and simplicity of a therapeutic trial, we favor including the low-normal Hgb group for a therapeutic trial of iron in order to avoid missing iron-responsive individuals among groups of infants with a similarly high prevalence of iron deficiency anemia.

This study was designed to compare the effectiveness of laboratory tests for iron deficiency (mean corpuscular volume, erythrocyte protoporphyrin, transferrin saturation, and serum ferritin) in predicting hemoglobin response to iron therapy in infants found to have low Hgb concentrations. Screening for anemia was performed on capillary blood of 1,128 healthy 1-year-old infants of United States Air Force personnel. The 25% who had Hgb values less than 11.5 gm/dl were asked to return for tests on venous blood before therapy and again after three months of therapy. Of the 188 infants completing therapy, 66 (35%) had a rise in Hgb concentration greater than or equal to 1.0 gm/dl and were designated responders. None of the confirmatory tests on venous blood reliably distinguished responders from those who subsequently showed no response. By using any one of the tests in combination with a capillary Hgb value less than 11.5 gm/dl, more than half of the infants with an abnormal value responded. But well over half of the responders would have been missed if treatment had been restricted to infants with abnormal values. Neither changes in the criteria for normality nor combinations of tests substantially improved our ability to distinguish the two groups. Because of the difficulty in distinguishing responders from nonresponders with additional laboratory tests and because of the simplicity, low cost, and relative safety of iron therapy in infants, we favor an initial therapeutic trial of iron first for determining the cause of low Hgb values in similar high-risk populations. Further costly workup can then be reserved for the small number of infants who still have unexplained Hgb concentrations less than 11.0 gm/dl after a therapeutic trial.

Initial screening for anemia was performed on a capillary blood sample in 800 apparently healthy one-year-old white infants. Twenty-six percent had a Hgb or MCV below the estimated tenth percentile of normal and were asked to return for blood counts on a venous sample. They were then started on a three-month course of oral iron. Of the 151 infants who satisfactorily completed the treatment regimen, 54 had a greater than or equal to 1 gm/dl rise in venous Hgb (2.8 infants treated/response). If conformation of the capillary by the venous values had been a prerequisite for treatment, the size of the treatment group would have decreased from 151 to 87, the response rate would have been improved to 2.0 infants treated per response, but 11 of the infants who had a greater than or equal to 1 gm/dl response would have been missed. Since toxicity from iron therapy is rare, either the use of capillary blood counts alone or in combination with venous values constitutes a satisfactory basis for a therapeutic trial of iron in similar populations. Further evaluation can then be reserved for the small number whose Hgb remains below the lower limit of normal after treatment.

Iron deficiency is a common problem in otherwise healthy children and in children with systemic disease. We have reviewed the pathophysiology, laboratory diagnosis, and systemic effects of iron deficiency. We have emphasized that routine screening procedures do not efficiently predict those otherwise healthy children who will demonstrate a therapeutic response to iron. Furthermore, in patients with certain systemic diseases the diagnosis of iron deficiency is complicated by the inflammatory process and the response to a therapeutic trial of oral iron is often blunted. Since the potential adverse effects of iron deficiency may be extensive, a therapeutic trial of iron is indicated to establish the diagnosis of iron deficiency if the index of suspicion is high and laboratory results are equivocal.

In this study of 467 healthy term infants seen for routine 1-year health maintenance examination, we determined the influence of mild prior infection on the concentration of hemoglobin and other laboratory evidence of iron deficiency. In addition we studied the Hgb response in 261 infants randomized to receive a 3-month course of treatment with either iron or placebo. Infants who had had one or more clinic visits because of infection during the previous 3 months or who were reported as not being entirely well during the past month or who had an elevated sedimentation rate were more likely to have anemia or "low normal" Hgb, higher erythrocyte protoporphyrin and serum ferritin values, and lower serum iron concentration than infants who had been well. Hgb response greater than or equal to 1 gm/dl after iron treatment occurred more commonly in infants who had had prior visits because of infection. The results indicate that upper respiratory and other mild antecedent infections commonly predispose to iron deficiency (probably because of a decrease in iron absorption).