Symptoms of Lead Exposure
Lead exposure causes a spectrum of symptoms ranging from subtle neurodevelopmental effects at low levels to life-threatening encephalopathy at high levels, with most children being completely asymptomatic despite significant cognitive impairment. 1
High-Level Lead Exposure (>100 μg/dL)
Very high blood lead concentrations produce acute, overt symptoms that constitute a medical emergency:
- Protracted vomiting 1
- Encephalopathy (altered mental status, seizures, coma) 1, 2
- Death if untreated 1
- Seizures 1, 2
Moderate to High-Level Exposure (Clinical Lead Poisoning)
When symptomatic, lead poisoning typically presents with:
- Severe colicky abdominal pain (often misdiagnosed as acute abdomen) 3, 4, 5
- Recurrent vomiting 1
- Anemia with basophilic stippling of red blood cells 2, 5
- Lethargy and fatigue 2, 6
- Headache and dizziness 4
- Lead line (blue-gray discoloration of gums) 5
- Peripheral neuropathy 6, 5
Low-Level Lead Exposure (<10 μg/dL)
The critical clinical reality is that most children with harmful lead exposure are completely asymptomatic, yet suffer permanent neurodevelopmental damage. 1 This is why screening rather than symptom-based detection is essential.
At blood lead levels below 10 μg/dL, and even below 5 μg/dL, children experience:
Neurodevelopmental Effects (Most Important for Morbidity)
- Decreased IQ scores (6.2 IQ point loss from <1 to 10 μg/dL) 1
- Impaired academic achievement 1
- Attention-related behavioral problems 1
- Hyperactivity and attention deficits 1
- Antisocial behaviors 1
Physical Effects
- Reduced postnatal growth and height 1, 2
- Lower birth weight 1
- Delayed puberty 1
- Decreased hearing acuity 1, 2
- Decreased kidney function (in children ≥12 years) 1
Cardiovascular Effects (Long-term)
- Hypertension (1.0-1.25 mmHg systolic increase per 2-fold blood lead increase) 7
Critical Clinical Pitfall
The absence of symptoms does not indicate absence of harm. 1 Children with blood lead levels of 5-10 μg/dL rarely show clinical symptoms but experience measurable cognitive impairment that is permanent and untreatable. 1 This creates a dangerous situation where the most common presentation of lead toxicity is no presentation at all—children silently lose IQ points without any outward signs. 1
No safe threshold for lead exposure has been identified—even levels below 5 μg/dL cause neurodevelopmental harm. 1 The relationship between lead and IQ is nonlinear, with proportionately greater IQ decrements at the lowest blood lead concentrations. 1
When to Suspect Lead Poisoning
Consider lead exposure in any child with:
- Unexplained anemia, especially with basophilic stippling 2, 5
- Recurrent or severe abdominal pain without clear etiology 3, 4
- Developmental delays or behavioral problems 1
- Living in housing built before 1978 (especially pre-1960) 8
- Recent home renovations 8
- Parental occupational exposure (battery recycling, construction, metallurgy) 5