Lead Poisoning
A 47-year-old man presented to the general medicine clinic with a 6-month history of wrist drop. He also reported a 3-year history of abdominal pain and constipation, a 14-month history of confusion, and a 1-year history of darkening of his tongue and gums. For the past 5 years, he had worked as a manual laborer in a lead–acid car battery factory. Physical examination was notable for tongue hyperpigmentation (Panel A) and gingival “lead lines” — bluish pigmentation along the gum line that is seen in patients with lead poisoning who have impaired dental hygiene (Panel B). Wrist drop of both arms (Panel C) plus impaired attention, working memory, and executive processing were observed on neurologic examination. Laboratory studies showed microcytic anemia, normal kidney function, a normal manganese level, and a blood lead level of 83 μg per deciliter (4.0 μmol per liter; reference value, <10 μg per deciliter [<0.5 μmol per liter]). A diagnosis of chronic lead poisoning was made. Chelation therapy was initiated. The patient stopped working in the factory, and the health care team reported the occupational exposure. At a 6-month follow-up visit, the blood lead level was 32 μg per deciliter (1.5 μmol per liter). The patient’s gastrointestinal and neurologic symptoms had abated, but the mucosal hyperpigmentation was unchanged.