Elevated Lead Levels in Children With Nonorganic Failure to Thrive

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Abstract
Every child with failure to thrive has at least one organic medical disease: malnutrition. It is well documented that lead and other heavy metals are absorbed more readily in the presence of both malnutrition and iron deficiency anemia. Malnutrition and lead exposure tend to be found in the same population groups. Furthermore, lead poisoning is correlated with many of the identical intellectual and behavioral deficits demonstrated in children suffering from nonorganic failure to thrive. Because of these facts whole blood lead levels were determined for 45 children with nonorganic failure to thrive and 45 age-, race-, and socioeconomically matched comparison subjects. Children with failure to thrive had a lead level of 22.67 .+-. 10.29 (.mu.g/dL (mean .+-. SD); for control children, it was 14.33 .+-. 5.42 (P < 0.001). Children with failure to thrive were more frequently anemic (P < 0.0001), a possible lead effect, and had higher free erythrocyte protoporphyrin levels. Children with failure to thrive were developmentally delayed on the Denver Developmental Screening Test (unblinded observation) with high failure rates in both language (P < 0.001)and gross motor skills (P < 0.02). Although failure on the Denver Developmental Screening Test within the failure to thrive group was not linearly correlated with lead level, any such effects may have been masked by the effects of malnutrition and failure to thrive per se. A number of authors have suggested that lead levels formerly thought to be inconsequential are clinically toxic. Lead levels in the 15- to 20-.mu.g/dL range interfere with heme synthetase activity and the synthesis of CNS neurotransmitters. Increased lead levels, malnutrition, and iron deficiency are all potentially etiologic in the developmental disabilities ascribed to failure to thrive. Pediatricians should screen all at-risk children with failure to thrive for elevations in lead levels, developmental delay, and iron deficiency. Given that malnutrition per se is synonymous with failure to thrive and may result in increased lead absorption, pediatricians should immediately take steps to ensure adequate caloric intake in children with failure to thrive. The treatment of such biomedical problems as elevated lead levels, malnutrition, and iron deficiency may ameliorate some of the behavioral, cognitive, and interactive deficits observed in nonorganic failure to thrive. Parenting difficulties observed in families with children who fail to thrive may be exacerbated by the child.