5-year-old male brought to casualty by his mother because of episode of sudden vomiting. He has been behaving strangely according to mother. Laboratory findings showed microcytic hypochromic anemia with the above finding. The most probable poisoning is:
**Core Concept**
Lead poisoning, especially chronic exposure, is a common cause of microcytic hypochromic anemia in children. It disrupts heme synthesis by inhibiting delta-aminolevulinic acid dehydratase (ALAD), leading to impaired erythropoiesis and characteristic blood findings.
**Why the Correct Answer is Right**
Chronic lead poisoning inhibits ALAD, the enzyme responsible for converting delta-aminolevulinic acid (ALA) to porphobilinogen in heme synthesis. This results in reduced hemoglobin production and microcytic, hypochromic anemia. In children, lead exposure is often due to ingestion of lead-based paints, toys, or contaminated soil. The clinical presentation includes behavioral changes, vomiting, and abdominal pain—key features in this case. Lead poisoning is a leading cause of neurodevelopmental and hematological abnormalities in pediatric patients.
**Why Each Wrong Option is Incorrect**
Option A: Arsenic poisoning typically causes macrocytic anemia or normocytic anemia, not microcytic hypochromic anemia. It also presents with gastrointestinal and neurological symptoms but does not specifically impair heme synthesis.
Option C: Mercury poisoning causes neurological symptoms and tremors but rarely leads to microcytic anemia. It is not associated with heme synthesis disruption.
Option D: Copper poisoning is extremely rare and usually causes hepatotoxicity or neurological symptoms, not anemia. It does not produce microcytic hypochromic anemia.
**Clinical Pearl / High-Yield Fact**
In children, **lead poisoning is the most common cause of microcytic hypochromic anemia** and should be suspected in any child with behavioral changes, vomiting, and abnormal blood counts. A blood lead level >50 µg/dL is diagnostic, and chelation therapy is indicated in severe cases.
✓ Correct Answer: B. Chronic lead poisoning