Clinical meaning
Lead poisoning in adults occurs primarily through occupational exposure (battery manufacturing, painting, plumbing, construction, shooting ranges) and environmental sources. Lead inhibits delta-aminolevulinic acid dehydratase and ferrochelatase enzymes in heme synthesis, causing microcytic hypochromic anemia with basophilic stippling on peripheral smear. Neurological effects include peripheral neuropathy (classically wrist drop from radial nerve palsy), encephalopathy, and cognitive impairment. Renal effects include chronic interstitial nephritis and proximal tubular dysfunction. GI effects include lead colic (severe abdominal cramping). Burton lines (blue-black lines at the gum-tooth margin) are a classic physical finding. Blood lead levels > 5 mcg/dL are considered elevated; symptomatic toxicity typically occurs > 40-50 mcg/dL in adults. Chelation therapy with EDTA, DMSA (succimer), or dimercaprol is used for significant lead burden.
Exam relevance
Risk factors: - Occupational exposure in construction, painting, battery recycling, shooting ranges - Living in homes built before 1978 with deteriorating lead paint - Drinking water from lead pipes or lead-soldered plumbing - Use of traditional remedies or cosmetics containing lead - Retained lead bullet fragments from prior gunshot wounds