Acute-subacute lead poisoning. Clinical findings and comparative study of diagnostic tests.

A prospective study of an epidemic outbreak of acute lead poisoning characterized by unusual clinical and analytic manifestations was carried out. Its source was traced to lead-contaminated flour. Thirty-two adult patients presented with classic clinical symptoms of saturnism; however, 13 severely poisoned patients simultaneously manifested unusual clinical features such as hemolytic anemia and multiorgan dysfunction. We compared the diagnostic value of the different toxicity markers in 68 of 136 adults exposed to lead. Porphyrin precursors, urine levels of lead, and results from an edetic acid-provocative test gave poor diagnostic information and low correlation values with lead levels in blood. However, erythrocyte delta-aminolevulinic acid dehydratase activity showed a closer correlation with lead levels in blood, although we observed a frequent overlap of results in severe cases. The test for levels of lead in blood was the most reliable, suitable, and simplest test performed, and gave the best correlation with the external dose of lead, the clinical situation, and the toxicologic effects described by 12 different analytic data.