Putting Prevention into Practice

An Evidence-Based Approach

Screening for Elevated Blood Lead Levels in Children and Pregnant Women

Am Fam Physician. 2008 Nov 15;78(10):1201-1202.

This clinical content conforms to AAFP criteria for evidence-based continuing medical education (EB CME). See CME Quiz on page 1145.

Case Study

B.C., a 28-year-old white orthodontist at 32 weeks' gestation, comes to your office for a routine prenatal visit. She brings her two-year-old son, C.C., who is due for his well-child visit. B.C.'s previous pregnancy was uncomplicated, and she has been healthy during the current pregnancy. C.C. is at the 60th percentile for height and weight, and his immunizations are up-to-date. The patient history reveals that the family lives in a house built three years ago. B.C. does not smoke or use alcohol, and she does not use lead-based cosmetics or pottery.

Case Study Questions

1. Which of the following is/are considered a risk factor for increased blood lead levels in children and adults?

  • A. Housing built before 1950.

  • B. Low income.

  • C. Minority race or ethnicity.

  • D. Rural residence.

2. Based on information from the U.S. Preventive Services Task Force (USPSTF), would you recommend obtaining a blood lead measurement for C.C.?

  • A. Yes, because all children should be screened for lead poisoning.

  • B. Yes, because C.C. is at increased risk of lead poisoning.

  • C. No, because children at C.C.'s age have lower mean blood lead levels than older children.

  • D. Yes, because interventions can prevent potential deleterious effects of lead poisoning.

  • E. No, because C.C. is asymptomatic and is not at increased risk of lead poisoning.

3. B.C. has heard reports that elevated lead levels in pregnant women may lead to poor health outcomes. She asks whether she should be tested for lead poisoning. Which of the following statements is correct?

  • A. She should be screened as part of routine prenatal care.

  • B. She should be screened because early intervention can prevent poor health outcomes.

  • C. She should be screened because she is at increased risk of lead poisoning.

  • D. She should not be screened because elevated blood lead levels in pregnant women have no deleterious effects on the fetus.

  • E. She should not be screened because she is asymptomatic.

Answers

1. The correct answers are A, B, and C. Risk factors for increased blood lead levels in children and adults include pre-1950 housing, low income, minority race and ethnicity, urban residence, low educational attainment, recent or ongoing home renovation or remodeling, pica, use of ethnic remedies or certain cosmetics, exposure to lead-glazed pottery, occupational and para-occupational exposures, and recent immigration. Additional risk factors for pregnant women include alcohol use and smoking.

2. The correct answer is E. A blood lead measurement is not recommended for C.C. because he is asymptomatic and is not at increased risk of lead poisoning. The USPSTF recommends against routine screening for elevated blood lead levels in asymptomatic children one to five years of age who are at average risk of the condition. The USPSTF found insufficient evidence (no studies) to recommend for or against routine screening in asymptomatic children at increased risk. The highest mean blood lead levels in the United States occur in children one to five years of age. Children in this age range are at greater risk of elevated blood lead levels and lead toxicity because of increased hand-to-mouth activity, increased lead absorption from the gastrointestinal tract, and the greater vulnerability of the developing central nervous system. However, the USPSTF found good-quality evidence that screening or interventions do not result in sustained decreases in blood lead levels in children. Good-quality evidence indicates that chelation treatment in asymptomatic children does not improve neurodevelopmental outcomes and is associated with a slight diminution in cognitive performance. Chelation therapy may result in transient renal, hepatic, and other toxicities; mild gastrointestinal symptoms; sensitivity reactions; and rare life-threatening reactions. Improper removal techniques during residential lead-based paint and dust hazard control treatments may lead to acutely increased blood lead levels.

3. The correct answer is E. B.C. should not be screened because she is asymptomatic. The USPSTF recommends against routine screening for elevated blood lead levels in asymptomatic pregnant women. Severely elevated blood lead levels in pregnant women are associated with poor health outcomes; however, blood lead levels in this range are rare in the U.S. population. The USPSTF concluded that, given this low prevalence, the potential benefit of screening would be small, at most. In addition, the USPSTF found no evidence examining the effectiveness of screening or interventions in improving health outcomes in asymptomatic pregnant women.

SOURCES

U. S. Preventive Services Task Force. Screening for elevated blood lead levels in children and pregnant women. Pediatrics. 2006;118(6):2514–2518.

Rischitelli G, Nygren P, Bougatsos C, Freeman M, Helfand M. Screening for elevated blood lead levels in childhood and pregnancy: an updated summary of evidence for the U.S. Preventive Services Task Force. Pediatrics. 2006;118(6):e1867–e1895.

The case study and answers to the following questions on screening for elevated blood lead levels in children and pregnant women are based on the recommendations of the U.S. Preventive Services Task Force (USPSTF), an independent panel of experts in primary care and prevention that systematically reviews the evidence of effectiveness and develops recommendations for clinical preventative services. More detailed information on this subject is available in the USPSTF Recommendation Statement and the evidence update on the USPSTF Web site (http://www.ahrq.gov/clinic/uspstfix.htm). The Recommendation Statement is available in print through the AHRQ Publications Clearinghouse (800-358-9295, e-mail, ahrqpubs@ahrq.hhs.gov). The practice recommendations in this activity are available at http://www.ahrq.gov/clinic/uspstf/uspslead.htm.


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