Lead Poisoning

Lead poisoning or lead toxicity generally occurs in 2 settings – childhood exposure or occupational exposure. The removal of lead from paint and gasoline in the 1970s resulted in lower blood-lead concentrations in the U.S.

  • Diagnosis
  • Screening
  • Monitoring
  • Background
  • Lab Tests
  • References
  • Related Topics

Indications for Testing

  • Adult
    • Risk of exposure or known lead exposure
    • Suspected or known occupational exposures
  • Pediatric
    • Pica
    • Developmental delay
    • Higher risk of exposure (CDC, 2015)
      • Parent, sibling, or friend with known lead poisoning
      • Low socioeconomic status
      • Minority
      • Recent immigrant
      • Older or poorly maintained living conditions

Laboratory Testing

  • Whole blood lead – preferred test
    • Elevated concentrations – confirm with a second specimen collected in a lead-free tube to exclude potential contribution of external contamination
    • ≥5 μg/dL – excessive for children and child-bearing females (CDC, 2008; Advisory Committee on Childhood Lead Poisoning Prevention [ACCLPP], 2012)
    • 30 μg/dL – Biological Exposure Index for whole blood lead levels in nonpregnant adults (American Conference of Governmental Industrial Hygienists [ACGIH] guidelines, 2007)
  • Urine lead testing – detect recent exposures to lead or monitor chelation therapy

Imaging Studies

Noninvasive measurements of lead in bone may be available via K-shell x-ray fluorescence – not widely available except in research settings

Differential Diagnosis

  • Porphyria
  • Other heavy metal toxicity (eg, arsenic) – follow state/local recommendations
  • Advisory Committee on Childhood Lead Poisoning Prevention (ACCLPP), 2012
    • Required for children 12-24 months enrolled in Medicaid
    • Consider non-Medicaid children between 12-24 months
  • U.S. Preventive Services Task Force (USPSTF) cannot recommend for or against screening
  • American Academy of Pediatrics (AAP) Bright Futures, 2015 – screen 6 months to 6 years
  • Plasma aminolevulinic acid, whole blood zinc protoporphyrin, or free erythrocyte protoporphyrins
    • Screening in occupational exposures
    • Presence not detected until lead concentrations reach ≥35 μg/dL
  • Urine lead
    • Detect acute exposure
    • Monitor chelation therapy
  • Blood lead – occupational exposure

Epidemiology

  • Prevalence – ~450,000 children in the U.S. have concentrations ≥5 μg/dL (CDC, 2012)
  • 95th percentile for blood-lead concentration for various age groups (The Fourth National Report on Human Exposure to Environmental Chemicals [CDC, 2009])
    • Children 1-5 years – 5.1 μg/dL
    • Children 6-11 years – 3.3 μg/dL
    • Adolescents 12-19 years – 2.6 μg/dL
    • Adults ≥20 years – 4.3 μg/dL

Risk Factors

  • Children – main source of exposure is leaded paint
    • Living in older housing, generally inner city areas
    • Low-income family
    • Midwest/Northeast residence
  • Adults – main source of exposure is occupational
    • Lead smelting, mining, ammunitions, soldering, plumbing, ceramic glazing, construction work
    • Use of ceramics with lead-based glaze
    • Use of herbal remedies from Asia

Pathophysiology

  • Exposure mainly through respiratory and gastrointestinal tracts
    • 30-40% of inhaled lead is absorbed
    • Gut absorption depends on nutritional status and age
      • Absorption is enhanced in children <6 years
      • Absorption may be lessened by adequate intake of iron, calcium, magnesium, alcohol, fat
  • Absorbed lead remains bound to erythrocytes for approximately 1 month and then distributes into soft tissues such as liver, kidney, and brain over 4-6 weeks
  • Final storage of absorbed lead
    • Bone
      • Children – 70% of absorbed lead
      • Adults – 80-95% of absorbed lead
    • Soft tissue sites – store remaining absorbed lead

Clinical Presentation

  • Children – clinical symptoms usually present with concentrations ≥60 μg/dL but may occur at much lower concentrations
    • Gastrointestinal – abdominal pain, constipation, colic
    • Central nervous system (CNS) – clumsiness, gait abnormalities, headache, behavioral changes, seizures
      • IQ declines seen at concentrations ≥10 μg/dL
      • Severe, persistent cognitive and behavioral problems
    • Hematologic – anemia
    • Renal – acute nephropathy
  • Adults – whole blood concentrations ≥30 μg/dL indicate significant exposure (WHO)
    • CNS – peripheral neuropathies, motor weakness
    • Renal – chronic renal insufficiency
    • Cardiovascular – systolic hypertension
    • Hematologic – anemia (normochromic/normocytic)
    • Gastrointestinal – abdominal pain, constipation, anorexia, nausea
Tests generally appear in the order most useful for common clinical situations. Click on number for test-specific information in the ARUP Laboratory Test Directory.

Lead, Blood (Capillary) 0020745
Method: Quantitative Inductively Coupled Plasma-Mass Spectrometry

Limitations 

Elevated results may be due to skin or collection-related contamination, including use of a noncertified lead-free tube

Follow-up 

Elevated levels of blood lead should be confirmed with a second specimen collected in a lead-free tube

Repeat testing is recommended prior to initiating chelation therapy or conducting environmental investigations of potential lead sources

Lead, Blood (Venous) 0020098
Method: Quantitative Inductively Coupled Plasma-Mass Spectrometry

Limitations 

Elevated results may be due to skin or collection-related contamination, including use of a noncertified lead-free tube

Follow-up 

Elevated levels of blood lead should be confirmed with a second specimen collected in a lead-free tube

Lead, Industrial Exposure Panel, Adults 0025016
Method: Quantitative Inductively Coupled Plasma-Mass Spectrometry/Hematofluorometry

Limitations 

Elevated results may be due to skin or collection-related contamination, including use of a noncertified lead-free tube

Lead, Urine 0025060
Method: Quantitative Inductively Coupled Plasma-Mass Spectrometry

Guidelines

Advisory Committee on Childhood Lead Poisoning Prevention. Low level lead exposure harms children: a renewed call for primary prevention. Centers for Disease Control and Prevention. Atlanta, GA [Published Jan 2012; Accessed: Aug 2017]

American Academy of Pediatrics. Bright Futures. Recommendations for preventive pediatric health care. Pediatrics. 2015; PubMed

CDC response to Advisory Committee on Childhood Lead Poisoning Prevention recommendations in “Low level lead exposure harms children: a renewed call of primary prevention”. Centers for Disease Control and Prevention. Atlanta, GA [Last updated Jun 2012; Accessed: Aug 2017]

CDC. Lead. Centers for Disease Control and Prevention. Atlanta, GA [Last updated Feb 2015; Accessed: Sep 2017]

Department of Health and Human Services, Centers for Disease Control and Prevention. Fourth National Report on Human Exposure to Environmental Chemicals. [Accessed: Aug 2017]

Kosnett MJ, Wedeen RP, Rothenberg SJ, Hipkins KL, Materna BL, Schwartz BS, Hu H, Woolf A. Recommendations for medical management of adult lead exposure. Environ Health Perspect. 2007; 115(3): 463-71. PubMed

Ness R. Practice guidelines for childhood lead screening in primary care. J Pediatr Health Care. 2013; 27(5): 395-9. PubMed

Rischitelli G, Nygren P, Bougatsos C, Freeman M, Helfand M. Screening for elevated lead levels in childhood and pregnancy: an updated summary of evidence for the US Preventive Services Task Force. Pediatrics. 2006; 118(6): e1867-95. PubMed

Wengrovitz AM, Brown MJ, Advisory Committee on Childhood Lead Poisoning, Division of Environmental and Emergency Health Services, National Center for Environmental Health, Centers for Disease Control and Prevention. Recommendations for blood lead screening of Medicaid-eligible children aged 1-5 years: an updated approach to targeting a group at high risk. MMWR Recomm Rep. 2009; 58(RR-9): 1-11. PubMed

General References

Chandran L, Cataldo R. Lead poisoning: basics and new developments. Pediatr Rev. 2010; 31(10): 399-405; quiz 406. PubMed

Hu H, Shih R, Rothenberg S, Schwartz BS. The epidemiology of lead toxicity in adults: measuring dose and consideration of other methodologic issues. Environ Health Perspect. 2007; 115(3): 455-62. PubMed

Rusyniak DE, Arroyo A, Acciani J, Froberg B, Kao L, Furbee B. Heavy metal poisoning: management of intoxication and antidotes. EXS. 2010; 100: 365-96. PubMed

Warniment C, Tsang K, Galazka SS. Lead poisoning in children. Am Fam Physician. 2010; 81(6): 751-7. PubMed

Woolf AD, Goldman R, Bellinger DC. Update on the clinical management of childhood lead poisoning. Pediatr Clin North Am. 2007; 54(2): 271-94, viii. PubMed

References from the ARUP Institute for Clinical and Experimental Pathology®

Bornhorst JA, Hunt JW, Urry FM, McMillin GA. Comparison of sample preservation methods for clinical trace element analysis by inductively coupled plasma mass spectrometry. Am J Clin Pathol. 2005; 123(4): 578-83. PubMed

Gehrie E, Keiser A, Dawling S, Travis J, Strathmann FG, Booth GS. Primary prevention of pediatric lead exposure requires new approaches to transfusion screening. J Pediatr. 2013; 163(3): 855-9. PubMed

Medical Reviewers

Last Update: October 2017