Lead poisoning is a special concern in children with certain risk factors, such as those living in older housing that contain lead-based paint. Blood lead screening is recommended at one and two years of age in high-risk children or at ages 24-72 months if they have not previously been screened. Since the 1970s, the cut-off level for blood lead that is considered "toxic" has been periodically lowered. Public health officials now say that blood lead levels ≥ 5 µg/dL are toxic. Prior to 1971, blood lead levels were not considered toxic until ≥ 60 µg/dL. Please note that there are many occupations, hobbies, and other activities that expose adults to lead, but they are not discussed in this course.
Lead has many damaging effects on RBCs secondary to damage to the RBC membrane. Many of the symptoms are manifested in the nervous and gastrointestinal systems. Hyperactivity, aggressive behavior, cognitive decline, and constipation are just some examples of childhood presentation of lead poisoning.
Microcytic, hypochromic anemia is expected in lead poisoning. Iron studies will be normal in these patients. Basophilic stippling has classically been associated with lead poisoning. It suggests toxic injury to the bone marrow, such as that caused by excessive lead, but basophilic stippling is neither specific nor sensitive to lead poisoning and can be seen in other conditions.
Erythrocyte/zinc protoporphyrin was discussed earlier in regard to iron deficiency anemia. Both iron deficiency anemia and lead poisoning cause increases in this analyte.
