Lead Poisoning

Clinical symptoms of lead toxicity occur in a dose-dependent manner, with individual variability. The most common initial symptoms are abdominal pain (lead colic) and other gastrointestinal symptoms (e.g., nausea, vomiting, constipation, diarrhea). Other affected systems include the central nervous (e.g., fatigue, malaise, impaired cognition, tinnitus, headaches, mood changes), peripheral nervous (e.g., peripheral neuropathy), hematologic (e.g., anemia with basophilic stippling), musculoskeletal (e.g., arthralgias, myalgias, saturnine gout), renal (e.g., impaired estimated glomerular filtration rate) and reproductive (e.g., decreased sperm count, decreased libido) systems.  Lead toxicity causes enzyme inhibition in the heme synthesis pathway, which can result in elevation of protoporphyrin levels.  Elevated lead levels are associated with adverse pregnancy outcomes including preterm birth, small-forgestational-age infants and pre-eclampsia. Prenatal lead exposure is associated with impaired cognitive development in children.

Removing the exposure to lead is the most important part of management. Ongoing lead exposure is generally a contraindication to chelation. The threshold for chelation of symptomatic patients is a blood lead level greater than 70–100 μg/dL, with lower thresholds for children and pregnant people.The quality of the evidence for the effectiveness of chelation is not strong; thus, the decision should be made on an individualized basis in consultation with an expert.With prolonged lead exposure, most lead is distributed to bone, with a smaller proportion to soft tissues, causing end-organ damage. The biological half-life of lead can be decades long in cortical bone. Chelation reduces blood lead levels, but little evidence indicates that it can access lead in bone. A rebound of blood lead levels can occur after chelation but usually not to the pre-chelation level.

Contact your health care provider, ER or Department of Public Health if you suspect possible lead exposure. DO NOT DELAY. A blood lead test can help identify whether a problem exists and appropriate therapy/amelioration may be initiated.

Author

Paddy Kalish OD, JD and B.Arch