Lead poisoning: case studies

Early clinical features of lead toxicity are non-specific and an occupational history is particularly valuable. Lead in the body comprises 2% in the blood (t(1/2) 35 days) and 95% in bone and dentine (t(1/2) 20-30 years). Blood lead may remain elevated for years after cessation from long exposure, due to redistribution from bone. Blood lead concentration is the most widely used marker for inorganic lead exposure. Zinc protoporphyrin (ZPP) concentration in blood usefully reflects lead exposure over the prior 3 months. Symptomatic patients with blood lead concentration >2.4 mumol l(-1) (50 mug dl(-1) ) or in any event >3.8 mumol l(-1) (80 mug dl(-1) ) should receive sodium calciumedetate i.v., followed by succimer by mouth for 19 days. Asymptomatic patients with blood lead concentration >2.4 mumol l(-1) (50 mug dl(-1) ) may be treated with succimer alone. Sodium calciumedetate should be given with dimercaprol to treat lead encephalopathy.