Lead Poisoning is the Most Likely Diagnosis
The combination of normocytic, normochromic anemia with basophilic stippling, target cells, and shredded RBCs in a preschool-aged child strongly indicates lead poisoning (Answer C). 1, 2
Key Diagnostic Features Supporting Lead Poisoning
The blood smear findings are highly characteristic:
- Basophilic stippling represents aggregated ribosomes within red blood cells and is a classic finding in lead toxicity, though it can occur in other conditions 1, 3
- Target cells and shredded RBCs indicate membrane damage and oxidative stress to erythrocytes, consistent with lead's toxic effects on heme synthesis 2, 3
- Normocytic, normochromic pattern is typical of lead poisoning, distinguishing it from iron deficiency which presents as microcytic, hypochromic 2, 4
- Normal WBC count helps exclude other systemic processes like chronic inflammation or malignancy 2
Why Other Options Are Less Likely
Iron deficiency anemia (Option A) would present with:
- Microcytic, hypochromic red cells, not normocytic 5
- Low ferritin and transferrin saturation 5
- Elevated RDW without basophilic stippling 5
Hypothyroidism (Option B) typically causes:
- Normocytic or macrocytic anemia 6
- Does not produce basophilic stippling or target cells 6
- Associated with other thyroid-related symptoms
Anemia of chronic disease (Option D) presents with:
- Normocytic anemia but elevated ferritin >100 μg/L 7
- Transferrin saturation <20% 7
- Does not typically show basophilic stippling 6
Critical Diagnostic Pitfall
Basophilic stippling is not pathognomonic for lead poisoning alone - it occurs in only 27% of various medical conditions and can even appear in normal individuals 8. However, when combined with the specific constellation of findings in this case (normocytic anemia, target cells, shredded RBCs in a preschool child), lead poisoning becomes the most likely diagnosis 1, 2.
Confirmatory Testing Required
To definitively confirm lead poisoning:
- Blood lead level - elevated levels (>5 μg/dL in children) confirm diagnosis 2, 3
- Urinary lead concentration - will be elevated 2, 3
- Zinc protoporphyrin (ZP) - elevated due to lead's inhibition of heme synthesis 3, 4
- Urinary porphyrins - increased excretion 2, 3
- Erythrocyte ALA-dehydratase - decreased activity 3
Source Investigation
In preschool children, common lead exposure sources include:
- Lead-based paint in older homes 3
- Contaminated soil or dust 3
- Imported ceramics or toys 2
- Contaminated water from lead pipes 2
Environmental assessment is mandatory once diagnosis is confirmed to prevent ongoing exposure 2, 3.