17-24: Lead Poisoning

Clinical Summary

Although the prevalence of markedly elevated lead levels in the population has been declining, acute and chronic lead poisoning still occurs. Lead is well absorbed by the lungs and less well absorbed via the GI tract. Lead paint in older homes is a continued source of lead exposure. Other possible exposures may occur from occupational exposures, retained lead bullets in synovial fluid, jewelry, lead-painted toys, fishing weights, ceramic glazes, and cosmetics. Severe lead poisoning in adults has also been associated with ingestion of contaminated moonshine.

Lead poisoning affects multiple organ systems. Neurotoxicity may range from subtle personality changes to encephalopathy and cerebral edema. At the societal level, even small lead burdens are associated with statistically significant decreases in intelligence quotient. Motor neuropathy such as foot drop and wrist drop may be seen in adult patients, especially after occupational exposure. Microcytic anemia may occur, and basophilic stippling of the red cells may be seen. Hypertension and an acute nephropathy may occur. Abdominal pain may be described by patients, but unlike other heavy metal poisonings, constipation is more likely than diarrhea. Radiographic “lead lines,” bands of increased density on long bone metaphyses, may be seen in young children. These densities are not due to deposition of lead but rather increased calcium deposition.

Management and Disposition

Whole blood lead level is the primary measure of lead exposure but is not usually available in real time. Radiographic studies may demonstrate radiopaque substances from ingested jewelry or paint chips in children. Lead encephalopathy must be aggressively managed. Dimercaprol (BAL) is administered intramuscularly and CaNa₂EDTA is later given intravenously. Chelation with oral succimer is currently recommended in asymptomatic children with levels between 45 and 70 µg/dL. Reducing the exposure in children is paramount to treatment, and the source of the lead may be elusive.

Pearls

1. One source of lead exposure in children is through the occupation of the parent. Workers in a lead dust environment will bring home the lead dust on their clothes and shoes.

2. Imported eye cosmetics with lead have been a source of pediatric exposures in certain ethnic groups.

3. Azarcon and greta are lead-based remedies that are used to treat diarrheal illnesses.

4. Adults usually require much higher blood lead levels than children before encephalopathy occurs.