Lead Poisoning

Key Features

• Results from chronic repeated exposure; rare after single ingestion

• Produces a variety of adverse effects on cellular function; primarily affects the nervous system, gastrointestinal tract, and hematopoietic system

• Lead is used in firearms ammunition, storage batteries, paints, pottery, plumbing and is found in some traditional Hispanic and Ayurvedic ethnic medicines

Clinical Findings

• Abdominal pain, constipation, headache, irritability

• Coma and convulsions in severe poisoning

• Chronic intoxication can cause learning disorders (in children) and motor neuropathy (eg, wristdrop)

Diagnosis

• Whole blood lead levels above 3.5 mcg/dL warrant public health investigation

• Blood lead levels

  • Levels between 1 and 25 mcg/dL have been associated with subclinical impaired neurobehavioral development in children

  • Levels of 25–60 mcg/dL may be associated with headache, irritability, subclinical neuropathy, slowed reaction time, and other neuropsychiatric effects

  • Levels of 60–80 mcg/dL are associated with moderate toxicity (eg, abdominal pain, constipation)

  • Levels > 80–100 mcg/dL are often associated with severe poisoning (eg, coma, convulsions)

• Microcytic anemia with basophilic stippling and elevated free erythrocyte protoporphyrin may be seen

Treatment

• Identify and remove the source of exposure

• If a lead object is visible on abdominal radiograph, whole-bowel irrigation, endoscopy, or surgical removal may be necessary

• Consult a medical toxicologist or regional poison control center for advice about chelation

• For severe intoxication (encephalopathy or levels > 80–100 mcg/dL), give edetate calcium disodium (EDTA), 1500 mg/m²/kg/day (~50 mg/kg/day) in four to six divided doses or as a continuous intravenous infusion

• Dimercaprol, 4–5 mg/kg every 4 hours intramuscularly for 5 days, is usually added if the patient is encephalopathic

• Less severe symptoms with blood lead levels between 55 and 69 mcg/dL may be treated with EDTA alone in dosages as above

• Succimer (dimercaptosuccinic acid), 10 mg/kg every 8 hours orally for 5 days, then every 12 hours for 2 weeks for mild to moderate cases