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A. Definitionnavigator

  1. Also known as plumbism
  2. Serum blood level >10 µg/dL
    1. This level is probably too high
    2. Blood levels ~3-10µg/dL associated with reduction in Intelligence Quotient (IQ) [4]
    3. Blood levels of 3µg/dL associated with delayed puberty and reduced height in girls [5]
  3. Natural blood level 0 µg/dL
  4. Current mean of American child is 3 µg/dL
  5. 9% of children have level above 10 µg/dL
  6. Increased Prevalence
    1. Minorities
    2. Low socioeconomic strata
    3. Urban families
    4. Higher prevalence in northeast where houses are older
  7. Chronic elevations of serum lead levels contribute to renal insufficiency [5]

B. Risk Factors and Lead Sourcesnavigator

  1. Age 6 to 24 months of age
  2. Nutritional deficiencies
    1. Iron or calcium deficiencies increase uptake
    2. High fat diet increases absorption
    3. Pica: an appetite for substances not fit for food
  3. Paint
    1. Lead added to paint starting in early 1900's
    2. Sale of lead paint banned in 1970's
    3. Most paint manufacturers had already voluntarily removed lead by this time
    4. About 50 million living units in US in 1992 had lead paint hazards
    5. Renovation of lead-laden homes produces significant lead dust
    6. A 0.5 cm lead paint chip can transiently raise serum paint levels by 10 mg/dL
  4. Soil: contaminated to depth of several inches
  5. Congenital: lead cross the placenta and is passed in breast milk
  6. Food: contamination of home grown vegetables or old cans with lead soldering
  7. Water: lead piping
  8. Air: leaded gasoline outlawed in 1994 by Clean Air Act

C. Screeningnavigator

  1. Classify as high or low risk depending on responses to screening questions
    1. Possible lead paint exposure
    2. Family member working around lead
    3. Residency near to an industry involving lead
  2. Low risk: screen at 12 and 24 months
  3. High Risk: screen more frequently and treat appropriately

D. Pathogenesisnavigator

  1. Lead binds irreversibly to the sulfhydryl groups of proteins
  2. Chemical modification impairs multiple enzymatic functions

E. Symptoms and Signsnavigator

  1. Often asymptotic and picked up at screening
  2. Chronic effects on central and peripheral nervous system
    1. Increased distractibility
    2. Impulsiveness
    3. Inability to follow directions
    4. Drop in IQ by 1-3 points for each increase in lead by 10 µg/dL
    5. This drop in IQ is only partially reversible with decline in lead levels over time [6]
  3. Anemia: microcytic or normocytic with basophilic stippling
  4. Burton's line: a bluish line on the free border of the gingiva
  5. Renal Dysfunction
    1. Fanconi type proximal tubular acidosis
    2. Elevated urinary prophyrins
    3. Contributes to progressive renal insufficiency [7]
  6. Acute Toxicity
    1. Anorexia
    2. Irritability
    3. Disturbed sleep
    4. Loss of developmental skills
    5. Persistent vomiting
    6. Ataxia
    7. Fluctuating mental status, stupor, encephalopathy
    8. Seizures (levels 100-150 µg/dL)
    9. Progression to coma
  7. Long Bone changes (radiodense) in children

F. Assessmentnavigator

  1. Many experts recommend routine screening of all children for blood lead levels
  2. Acceptable levels now reduced to 10µg/dL (was 25µg/dL)
  3. Reduced use of lead paint and leaded gasoline contributes to declining levels
  4. Screening should be followed up with attention to symptoms and signs

G. Treatmentnavigator

  1. Environmental inspection and hazard reduction
  2. Nutritional supplementation with iron and calcium and avoidance of high fat food
  3. Chelation Therapy
    1. Oral - DMSA (2,3-dimercaptosuccinic acid)
    2. Parenteral - EDTA
    3. Chelation therapy should be given for levels >20µg/dL
  4. Succimer (2,3 dimercaptosuccinic acid)
    1. Approved oral chelation therapy
    2. Chelates and reduces lead, other toxic heavy metals including mercury and arsenic
    3. Does not lead to improved scores on cognition, behavior, or neuropsychological tests [8]
    4. Dosage is 30mg/kg for 7 days (available in 100mg tablets)
    5. Can be given as tid for 5 days, then bid for 14 days also
    6. Half life is ~2 days
    7. 15 days post initial weekly treatment lead levels are ~60% of pretreatment levels
    8. Side effects mild transaminase elevations; rashes in 4% of patients
    9. Pregnancy category C; some teratogenicity generated in animal studies
  5. EDTA (calcium salt) chelation was mainstay of therapy
    1. Intravenous administration required
    2. Side effects include renal tubular necrosis
    3. Lead concentrations in brain and liver may be increased following therapy
    4. Chelation therapy for patients with elevated body lead reduces renal decline [7]
  6. Treatment recommendations based on lead level
    1. Lead level 0-9µg/dL: no interventions needed
    2. 10-19µg/dL: environmental survey, nutritional changes, and education; start iron to compete for intestinal absorption
    3. 20-24µg/dL: remove from lead source and consider chelation therapy
    4. 25-54µg/dL: oral chelation therapy indicated
    5. >55µg/dL: parenteral chelation therapy indicated

References navigator

  1. Rogan WJ and Ware JH. 2003. NEJM. 348(16):1515 abstract
  2. Berlin CM. 1997. Current Opin in Pediat. 9(2):173 abstract
  3. Trachenberg TE. 1996. Postgrad Medicine. 99(3):207 abstract
  4. Canfield RL, Henderson CR Jr, Cory-Slechta DA, et al. 2003. NEJM. 348(16):1517 abstract
  5. Selevan SG, Rice DC, Hogan KA, et al. 2003. NEJM. 348(16);1527 abstract
  6. Tong S, Baghurst PA, Sawyer MG, et al. 1998. JAMA. 280(22):1915 abstract
  7. Lin JL, Ho HH, Yu CC. 1999. Ann Intern Med. 130(1):7 abstract
  8. Rogan WJ, Dietrich KN, Ware JH, et al. 2001. NEJM. 344(19):1421 abstract