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Lead Toxicity
Initial Check

Course: WB 1105
CE Original Date: August 20, 2007
CE Renewal Date: August 20, 2010
CE Expiration Date: August 20, 2012
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Instructions

This Initial Check will help you assess your current knowledge about lead toxicity. To take the Initial Check, read the case below, and then answer the questions that follow.

Case Study

A father brings his two-year-old boy into a pediatrician's office for a routine well-child visit. From the father, the doctor learns that the boy's parents are divorced and that he generally lives with his mother and her parents. (The mother had to accompany her parents to her aunt's funeral this weekend and therefore could not make the appointment.) The doctor makes a note of this information.

The pediatrician examines the boy and finds no abnormalities. The boy's growth and development indicators are within normal limits for his age.

Three years later, concerned that her child is hyperactive, the mother brings the same child, now five years old, to your office (his previous pediatrician recently retired). At a parent-teacher conference last week, the kindergarten teacher said that the boy seems impulsive and has trouble concentrating, and recommended evaluation by a physician as well as by the school psychologist. The mother states that he has always seemed restless and easily distracted, but that these first six months in kindergarten have been especially trying.

He has also complained recently of frequent intermittent abdominal pains and constipation. The mother gave him acetaminophen for stomach pains with little change, and has been giving him a fiber laxative, which has reduced the frequency and severity of constipation. She wonders if the change to attending kindergarten has a role in his increased complaints.

Family history reveals that the boy lives with his sister, mother, and maternal grandparents in an older suburb of your community. The child visits with his father one weekend a month, which is working out fine. However, he seems to be fighting more with his sister, who has been diagnosed with attention-deficit disorder and is repeating first grade. Since the mother moved in with her parents after her divorce four years ago, she has worked with the grandfather in an automobile radiator repair shop, where her children often come to play after school. She was just laid off, however, and expressed worry about increasing financial dependence on her parents. She also worries that the grandfather, who has gout and complains increasingly of abdominal pain, may become even more irritable when he learns that she is pregnant.

Her third child is due in 6½ months.

On chart review, you see that the previous pediatrician examined the boy for his preschool physical one year ago. A note describes a very active four year old who could dress himself without help but could not correctly name the primary colors. His vision was normal, but hearing acuity was below normal according to a hearing test administered for his preschool physical. The previous doctor noted that the boy's speech and language abilities were slightly delayed. Immunizations are up to date.

Further history on last year's visit indicated adequate diet, with no previous pica behavior. Hematocrit was diminished at 30%. Peripheral blood smear showed hypochromia and microcytosis. There was no evidence of blood loss, and stool examination was negative for occult blood. The diagnosis was “mild iron deficiency anemia,” and elemental iron 5 mg/kg per 24 hours (three times daily after meals) was prescribed. The family failed to keep several follow-up appointments, but the child did apparently complete the prescribed 3-month course of iron supplements. He receives no medications at this time and has no known allergies.

On physical examination today, you note that the boy is in the 10th percentile for height and weight. The previous year he fell within the 20th percentile. His attention span is very short, making him appear restless, and he has difficulty following simple instructions. Except for slightly delayed language and social skills, the boy has reached most important developmental milestones.

Initial Check Questions

  1. Is there any information that the previous physician should have asked about or looked for (or did not note down) when the boy was brought in as a two year old?
    1. whether either parent smoked
    2. age and condition of boy's primary residence and occupations of family members
    3. the child's birth weight
    4. whether the child takes vitamins
  2. What should be included in this boy's problem list?
    1. delayed language ability, slightly impaired hearing
    2. short stature, anemia and abdominal pain
    3. possible attention deficit disorder
    4. All of the above
  3. What test would you order to confirm or rule out your diagnosis?
    1. capillary blood draw (fingerstick)
    2. abdominal radiograph
    3. venous blood lead level
    4. erythrocyte protoporphyrin (EP) / zinc protoporphyrin (ZPP)
  4. Which other family member is at greatest risk for effects of lead exposure at this time?
    1. the mother
    2. the older sister
    3. the unborn baby
    4. the grandfather

Initial Check Answers

  1. Is there any information that the previous physician should have asked about or looked for (or did not note down) when the boy was brought in as a two year old?

    Answer B. Age and condition of boy's primary residence and occupations of family members

    Two of the obvious sources of lead suggested in the case study are leaded paint at home (paint flakes, household dust, and soil) and fumes and dust from solder at the radiator repair shop. You can ask questions about the age of the family's house, when it was most recently painted, and the condition of the paint to get a preliminary sense of the potential extent of this exposure pathway. If the house was built before 1978, the child may be exposed to lead paint chips, lead-contaminated soil, or lead in dust in the home.

    Additionally, you should determine if the boy ever had pica (a compulsive eating of nonfood items, to be distinguished from normal hand-to-mouth behavior of children). Pica is more common in children aged two to five, so it is unlikely that this is a present behavior. You can also ask about the length, type, and precise location of the boy's play at the radiator shop.

    The previous pediatrician would have done a better job if he or she had asked about the condition of the boy's primary residence as well as the occupations of mother and father.

    The information for this answer comes from section How Should Patients Exposed to Lead be Evaluated?.

  2. What should be included in this boy's problem list?

    Answer D. All of the above

    History suggests delayed language ability, slightly impaired hearing, short stature, possible attention deficit disorder, anemia and abdominal pain. The child is also experiencing passive exposure to his mother's cigarette smoke and family disruption and possible stress related to his parents' divorce or possibly attending kindergarten.

    The information for this answer comes from section How Should Patients Exposed to Lead be Evaluated?.

  3. What test(s) would you order to confirm or rule out your diagnosis?

    Answer C. Venous blood lead level

    To confirm lead poisoning, the best test is a venous blood lead level. Capillary blood draws (fingersticks) are not considered reliable for diagnosis purposes. A venous or a screening capillary BLL, is usually the first test drawn, instead of the EP/ZPP. Erythrocyte protoporphyrin (EP), commonly assayed as zinc protoporphyrin (ZPP) is not sufficiently sensitive at lower BLLs and therefore is not as useful a screening test for lead exposure in children.

    If the blood lead level is below 25 µg/dL, then a serum ferritin level and other iron studies can be used to determine if iron deficiency anemia exists.

    The information for this answer comes from section What Tests Can Assist with Diagnosis of Lead Toxicity?.

  4. Which other family member is at greatest risk for effects of lead exposure at this time?

    Answer C. The unborn baby

    The mother has recently been laid off, ending the potential occupational exposure. The grandfather may be exposed, as he shows irritability and abdominal pain. Therefore, if this source is removed he should recover. You should, however, suggest that he be tested and talk to his physician about it. The older sister might be at risk from exposure in the home or automotive repair shop, although because she is older she probably will ingest less lead through hand to mouth behavior at this time. However, her history also suggests she may have been exposed as a younger child as well.

    The unborn baby is at risk from several sources if the mother has current or past exposure, since lead stored in the bones is mobilized during pregnancy and passed to the fetus through the mother's blood. In addition, the baby will be at risk to potential home-based sources when he or she begins to move around and mouth objects. Prenatal exposure and exposure at a very young age to lead can damage development of the brain.

    The information for this answer comes from section What Are the Physiologic Effects of Lead Exposure?.

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