Snapshot A 56-year-old man presents with fatigue, pallor, and abdominal pain. The patient reports memory loss and further questioning reveals that he works at a battery recycling plant. On physical exam there is bluish lines on his gingivae at the base of his teeth, as well as noticeable foot drop. Laboratory testing is significant for a lead level > 10 μg/dL. Introduction Lead poisoning can affect many different organs, such as the the nervous system, hematopoietic system, liver, and kidneys Pathogenesis lead inhibits key enzymes in heme synthesis pathway inhibits ferrochelatase and ALA dehydratase results in ↓ heme synthesis results in ↑ RBC protoporhyrin lead inhibits rRNA degradation RBCs retain clumps of rRNA leads to basophilic stippling lead causes toxicity primarily through the generation of reactive oxygen species half-life of ~30 days in the blood, giving it time to diffuse into organs half-life of several decades in the bone, causing chronic lead poisoning Epidemiology major risk factor is old homes (painted or made before 1974) with chipped paint occupational exposures workers at battery recycling plants patients with pica may be at increased risk inner city children Prognosis depends on level of exposure, age, and treatment Presentation Symptoms, typically nonspecific, result from lead toxicity abdominal colic (lead colic) nausea vomiting anorexia pain toxicity to renal tubues interstitial nephritis reversible with therapy CNS abnormalities memory loss confusion encephalopathy headache mild anemia hypertension Physical exam Burton's lines, or lead lines, on gingival tissue at base of the teeth peripheral neuropathy, more commonly in adults wrist and food drop hyperactivity or hypoactivity loss of developmental milestones in children pallor Evaluation Best initial test ↑ level of free erythrocyte protoporphyrin (FEP) note iron deficiency anemia may also produce an ↑ in FEP capillary lead level Most accurate test for lead poisoning ↑ lead level (> 10 μg/dL) on venous sampling Other labs ↓ MCV and TIBC ↑ serum iron and ferritin Most accurate level for sideroblastic anemia Prussian blue stain on peripheral blood smear detects iron buildup in RBC mitochondria Other findings on peripheral blood smear basophilic stippling also seen in anemia of chronic disease, alcohol abuse, and thalassemias hypochromic microcytic RBCs Imaging radiograph showing Burton's lines, or lead lines and on long bone metaphyses Differential Diagnosis Iron deficiency anemia Mercury toxicity Treatment Chelating agents - indicated when lead levels > 44 μg/dL first-line - succimer (oral agent) second-line - penicillamine (oral agent) for severe disease or lead encephalopathy dimercaprol plus EDTA (pareneteral) dimercaprol crosses blood brain barrier Complications Particularly concerning in children as lead may affect the developing brain Death may result from ↑ intracranial pressures associated with lead encephalopathy Long-term effects lower sperm count ↑ in miscarriages and smaller babies