Which test is recommended for diagnosing lead poisoning in children?

• A. Erythrocyte protoporphyrin
• B. Urine delta-aminolevulinic acid
• C. Whole blood lead
• D. Zinc protoporphyrin

Answer: (C)

Measuring lead level in whole blood is the decisive test for diagnosing lead poisoning in children. This directly reflects recent exposure and body burden, providing a clear, specific indication of lead presence that guides management and treatment thresholds. The other markers—erythrocyte protoporphyrin and zinc protoporphyrin—are indirect indicators of disrupted heme synthesis or iron status and can be influenced by factors other than lead exposure, so they are not used to establish a diagnosis on their own. Urine delta-aminolevinulic acid is a metabolic byproduct that can rise with lead exposure but is less specific and not reliable as a standalone diagnostic test. In practice, a blood sample is used, with whole-blood lead measurement by appropriate analytical methods, to confirm exposure and assess severity.