Lead Poisoning
Plumbism

 

• Pica
  • Defined as persistent eating of non-nutritive material for 1 month or more
  • Always search for lead lines in any child with an ingested foreign body
• Main source of lead intoxication is lead paint used in houses painted before 1980
• Absorption is greater in children than adults
  • Lead may be inhaled as well as ingested
    • Symptoms develop more quickly through GI tract
    • Toxicity more severe with co-existing iron, zinc, or calcium deficiency
• Pathology
  • Lead concentrates in metaphyses of growing bones
    • Distal femur
    • Both ends of tibia
    • Distal radius leading to
      • Failure of removal of calcified cartilaginous trabeculae in provisional zone
• Clinical findings
  • Neurological
    • Learning disability
    • Decreased IQ
    • Mental retardation
    • Encephalopathy
    • Motor deficits
    • Seizures
    • Cerebral edema
    • Hearing loss
  • Gastrointestinal
    • Abdominal pain
    • Nausea
    • Vomiting
    • Diarrhea
    • Constipation
    • Anorexia
    • Metallic taste in mouth
    • Ileus
  • Renal
    • Tubular damage
      • Azotemia
    • Gout
  • Hematologic
    • Affects blood synthesis
    • Hemolysis
    • RBC stippling
    • Iron deficiency
  • Musculoskeletal
    • Muscle and joint pain
  • Soft tissue
    • Blue-black line in gum margins
  • Endocrine
    • Decreased stature
      • Decreased growth hormone
    • Decreased vitamin D levels
• Laboratory findings
  • Predate bone changes on x-ray
  • Serum Lead Level >1.2 umol/L
  • Urine lead level elevated
  • Peripheral Smear
    • Stippled erythrocytes
  • Complete Blood Count
    • Microcytic Anemia
    • Leukocytosis
  • Urine microscopy of sediment or renal biopsy
    • Acid-fast inclusion bodies in tubular nuclei
      • Pathognomonic for lead poisoning
  • Free Erythrocyte Protoporphyrin (FEP) > 0.6 umol/L
• Imaging findings
  • Cerebral edema in acute lead intoxication
  • Particles of lead in GI tract
  • Bands of increased density at metaphyses of tubular bones (growing bone)
    • Metaphyses of growing bones may be dense normally
      • Lead lines more apt to be seen in proximal fibula and distal ulna where growth is not as great as other long bones
    • Lead lines may persist

Frontal radiograph of both knees of a child with lead poisoning show dense metaphyseal bands
involving not only distal femurs and proximal tibias but proximal fibulas as well

• Bone-in-bone appearance
• Abnormalities in bone modeling
  • Erlenmeyer flask appearance to distal femur

• DDx (see tables below)
• Treatment
  • Surgical removal of lead foreign bodies in the gut (e.g. dice containing lead) if not eliminated within 2 weeks
  • Chelation is indicated if the level is greater than 45 mcg/dL even if asymptomatic
    • First correct iron deficiency
  • Chelating agents include EDTA, BAL, D-Penicillamine, and Succimer

Lucent Metaphyseal Bands Normal Leukemia Neuroblastoma TORCH infection

Dense Metaphyseal Bands Normal Lead poisoning Treated leukemia Healing rickets