Blood Lead Level (µg/dL) |
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10 - 14 |
15 - 19 |
20 - 44 |
45 - 69 |
>$70 |
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Lead education -Dietary -Environmental Follow-up blood lead monitoring
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Lead
education Proceed
according to actions for 20-44 µg/dL if: |
Lead education
Complete history
Lab work: Environmental investigation Lead hazard reduction
Neurodevelop-
Abdominal X-ray |
Lead education
Complete history
Lab work: Environmental investigation Lead hazard reduction
Neurodevelop-
Abdominal X-ray Chelation therapy |
Hospitalize and commence chelation therapy Proceed according to actions for 45-69 µg/dL |
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The following actions are
NOT recommended at any blood lead level: |
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Case
management of children with elevated blood lead levels (EBLLs) requires
a different approach from that used in the past. Prior to the
development of programs aimed at screening children for EBLLs, lead
exposure was generally not detected until a child presented with
symptoms of lead toxicity. Neurological findings associated with acute
encephalopathy (lethargy, ataxia, seizures, papilledema, and coma) were
often the first signs of an EBLL, and children with these symptoms
required immediate hospitalization and treatment. Encephalopathy could
result from a blood lead level (BLL) >=70 µg/dL
and could develop without prior symptoms. Among children with BLLs
exceeding 150 µg/dL, laboratory
abnormalities often included phosphaturia, proteinuria, aminoaciduria,
glucosuria, and hypophosphatemia (1-3).
Today such presentations are rare.
Children with EBLLs usually have BLLs below 30
µg/dL, and few BLLs
exceed 50 µg/dL. Most children with EBLLs have no symptoms. Case
management now focuses on reducing children’s exposure to lead and
decreasing their BLLs, whether they have symptoms of lead toxicity or
not. What follows is a guide to the basic standards and principles of
medical case management. It is not intended for use as a complete
protocol but rather as a tool for adapting management to local needs and
conditions.
General Principles of Medical Case Management
Coordinating Care
Coordination of care is critical to successful case management. For each child, an individualized plan of follow-up must be devised and implemented. Members of the case management team need to maintain open lines of communication and work together. Case managers and primary care providers (PCPs), in particular, must work collaboratively to ensure proper medical management and follow-up.
Conducting Medical Case Management
Medical case management for children with EBLLs is largely predicated on a
secondary prevention model (i.e., intervention after an EBLL has been
detected, usually prior to the onset of symptoms). By interrupting the
process of lead poisoning through early detection and intervention, case
managers working with PCPs can prevent children from dying or suffering
severe permanent sequelae of lead toxicity such as persistent seizures and
mental retardation (4, 5).
The detrimental effects of EBLLs in the
range of 10 to 45 µg/dL are usually subclinical and may include
neurodevelopmental impairment often apparent only at a later age. (See
Chapter 5, "Developmental Assessment and Intervention.") Figure
3.1 illustrates the lowest reported BLLs for some of the effects associated
with EBLLs. If a child presents without symptoms, the child’s PCP and case
manager may have trouble convincing the child’s caregiver of the
importance of suggested interventions. Case managers should manage each
child individually, taking into consideration the child’s BLL and the
ability of caregivers to cooperate and implement interventions.
Identifying Children with EBLLs
Screening programs are the main vehicle for identifying children with EBLLs. Those found in this manner typically have BLLs from 10 to 30 µg/dL and present with no abnormalities on routine medical history, physical examination, or laboratory tests (other than their EBLL). It is critical that case managers as well as PCPs not equate the absence of clinical symptoms, physical abnormalities, or abnormal laboratory results with an absence of toxicity.
Identifying Sources of Lead Exposure
When evaluating a child with an EBLL, case managers must identify the sources of a child’s lead exposure. The most common source of lead in children with EBLLs is leaded paint. Housing built before 1950 has been shown to be routinely contaminated with lead and to represent a risk for children (6, 7). Contamination of dust or soil occurs when leaded paint chalks or chips, or is subject to friction. (See Chapter 2, "Assessment and Remediation of Residential Lead Exposure.") Other less common sources include lead in water, lead in substances used in caregiver hobbies or occupations, lead in culturally specific substances such as folk remedies, and lead in imported cookware or cosmetics (Appendix 1).
General Considerations
Although abdominal pain, vomiting, constipation, change in appetite, and irritability have been described in association with EBLLs, they are seldom caused by BLLs less than 40 µg/dL, and other causes for such symptoms should be sought. Case managers, caregivers, and PCPs may note increased activity among children with BLLs < 45 µg/dL. However, they should not assume that increased activity is related to the EBLL (5, 8).
History Taking to Determine Lead Sources
A child’s environmental history can provide information about the child’s possible exposure to residential and other sources of lead. It should:
Taking
a history in the child’s home allows for direct observation and further
in-depth questioning. If a child’s BLL remains elevated despite lead
hazard reduction, less common sources should be considered. Because a child
may be exposed to lead from multiple sources, identifying one source may not
be sufficient to eliminate all lead exposure. Repeated history taking by
different members of the management team is often required.
Because knowledge about the lead
sources in a community and the prevalence of EBLLs in specific geographic
areas of the community can be useful in determining sources of exposure, the
interpretation of a child’s environmental history may require consultation
with lead experts. Case managers play a crucial role in treating children’s
EBLLs by fostering a multi-disciplinary approach to the environmental
evaluation and by coordinating communication among public health officials,
PCPs, and caregivers. Table 3.2 outlines suggested questions to ask in
determining a child’s environmental history. This is only intended to be a
guide, and case managers and PCPs are encouraged to tailor this list to
local needs.
Table 3.2. Guidelines for Questions to Ask Regarding a Child’s
Environmental History
Paint
and soil exposure
What is the age and general condition of the residence? Relevant behavioral characteristics of the child To what degree does the child exhibit hand-to-mouth activity? Exposures to and behaviors of household members What are the occupations of adult household members? Miscellaneous questions Does the home contain vinyl mini-blinds made overseas and purchased before
1997? |
Case managers should consider the following elements in assessing a child’s exposure to lead in paint or soil:
Relevant child behaviors
While pica has long been a known risk factor for EBLLs, typical hand-to-mouth activity during the toddler years is a more frequent cause of lead ingestion (18, 19). Although no supporting data are available, frequent hand washing may help lower EBLLs of young children.
Caregiver exposures and at-risk behaviors
Household members who work in lead-contaminated environments or participate in certain hobbies can bring lead into the home on their clothing or shoes (20). It is important to ask such household members whether they regularly shower and change clothes and shoes after these activities. Caregivers may also introduce airborne lead into the home by burning lead-contaminated materials in an indoor fireplace. (See Appendix I for a detailed discussion of caregiver exposures.)
Miscellaneous
Water: When no other
source of lead is found, the water supply should be considered. (See Chapter 2,
"Assessment and Remediation of Residential Lead Exposure.") While
public water systems must monitor, and, if necessary, treat tap water for
elevated lead levels, regulations governing lead in drinking water do not apply
to households supplied by private wells. Municipal water companies and private
industrial laboratories can advise case managers and caregivers on how to
collect and process water. In areas where there are no known hazardous
water-supply lines, lead contamination of the water may occur within the home
from lead solder in plumbing fixtures or from fixtures made of lead-containing
alloys. Contamination is increased when the water is relatively acidic (pH <
6.5). Moore found that water lead levels and the subsequent BLLs of children
drinking such water substantially decreased when the pH of drinking water was
raised to > 8.5. He also found that low mineral content increased lead
contamination in water, but not as greatly as acidity (21). Water that is hot or
has been stationary in pipes overnight contains more lead than freely running
cold water. Lead contamination decreases with the aging of home plumbing,
particularly if the water supply is alkaline or contains significant calcium or
other mineral deposits (22, 23).
Mini-blinds: Imported
vinyl mini-blinds may contain lead and result in exposure. (See Appendix I.)
Cultural practices:
Specific ethnic groups may use imported folk remedies, cosmetics, food, or
cookware contaminated with lead. Practices resulting in lead exposure from these
sources are often localized, and determining children’s risk from such
practices requires knowledge about a specific group’s cultural habits.
Caregivers may be reluctant to admit using some of these items, and it is
important not to put them on the defensive when taking the history. (See
Appendix I.)
Newly identified sources:
In the past, various items have emerged as lead hazards, often first presented
through the news media. Case managers and PCPs should be cognizant of recent
media and Consumer Product Safety Commission reports that may be relevant to
children with whom they have contact (see http://www.cpsc.gov).
Children evaluated as a
consequence of an EBLL found by screening most often have no physical findings
specific for lead toxicity. Gingival lead lines, although often stressed during
medical training, are rarely seen in clinical practice and are of no use in the
diagnosis and management of children with EBLLs. Pallor, papilledema, and other
neurologic findings suggestive of acute encephalopathy would not be expected.
A thorough evaluation of all
children with BLLs >=20 µg/dL is recommended for three reasons. First, it will
allow PCPs to ascertain whether children with such EBLLs have any findings
suggestive of encephalopathy. The BLL threshold for encephalopathic findings is
believed to be 70 µg/dL, although encephalopathy is usually associated with much
higher BLLs (1, 3). Second, it will allow PCPs to assess whether children
with EBLLs are engaging in at-risk behaviors such as pica and hand-to-mouth
activity. Finally, it will allow PCPs to identify behavioral and
neurodevelopmental disorders, such as distractibility, aggression, or speech
delay. If a child has any of these findings, regardless of their etiology, the
case manager or PCP should, when appropriate, refer the child for a further
evaluation. (See Chapter 5, "Developmental Assessment and
Interventions.")
Laboratory and Imaging Evaluation
Among asymptomatic children, most clinical laboratory results other than
BLLs will be normal and therefore will not be of assistance in case
management. However, all children should have a hemoglobin or hematocrit
test performed, as anemia is associated with EBLLs. That iron deficiency
rather than lead is the cause of such anemia does not diminish the need
for follow-up (24, 25). PCPs may wish to assess children’s
iron stores by one or more of a variety of laboratory tests. Iron
deficiency may delay children’s neurodevelopment independently of the
effects of lead (26). Because basophilic stippling is not specific
for lead toxicity, a peripheral blood smear is of no use in the
hematologic evaluation.
The inhibition of heme synthesis
leads to the accumulation of excess porphyrins, particularly
protoporphyrin IX in red cells. The fluorescence of these porphyrins has
led to the development of methods to detect extracted porphyrins—free
erythrocyte protoporphyrin (FEP) or erythrocyte porphyrin (EP) testing—and
to the observation of zinc protoporphyrin (ZPP) in red cells. Because the
relationship between the results of these tests and BLLs is log-linear,
these tests can be used to evaluate and follow children with very high
BLLs. However, the results are confounded by concomitant iron deficiency
and show poor correlation with BLLs <=25 µg/dL
(27). Therefore, EP tests should be used infrequently except in
evaluating children with BLLs well above 25 µg/dL
whose BLLs do not show a steady decline in response to medical and
environmental interventions. In such situations, these measures may assist
PCPs in differentiating BLL rebound after treatment from the effects of
re-exposure.
While very high BLLs have been
associated with serious to severe renal tubular dysfunction (2, 28),
there is no evidence to support routinely evaluating the renal status of
children with presymptomatic BLLs. However, if potentially nephrotoxic
chelating agents such as EDTA are to be used in treatment, renal function
testing is appropriate prior to and during therapy.
Abdominal radiographs may be useful
in determining whether children are currently ingesting lead-contaminated
non-food items, including paint chips. They are particularly useful when
children have an unexpected acute rise in BLL or are not responding to
case management as expected. Long-bone films for the presence of growth
arrest lines ("lead lines") may be of interest but rarely
provide information useful for a child’s case management (29).
Lead lines are not present unless BLLs exceed 50 µg/dL
and are indicative of chronic exposure (30). Also of no documented
utility in the management of children with EBLLs are hair (31),
fingernail, and tooth (dentin) lead measurements. Hair and fingernails are
subject to external contamination, which makes the results of lead tests
on them uninterpretable.
A few studies have demonstrated
alteration of neurophysiologic function (e.g., postural sway, auditory
evoked potentials, nerve conduction) with BLLs observed today (32-35).
However, further research is needed to define normative standards and
determine inter-individual variation and clinical significance. Until
then, such measures are of little use in the diagnosis or
management of an individual child.
X-ray fluorescence of long bones uses
a radioactive source to provide noninvasive estimation of lead in bone (36).
At the present time, it should be considered a research tool to be used
only to characterize groups of children in epidemiological studies. As
with the neurophysiologic methods discussed previously, it is
insufficiently standardized, and results show significant inter-laboratory
variation.
While chelation therapy is considered a mainstay in the medical management
of children with BLLs > 45 µg/dL, it
should be used with caution. Primary care providers should consult with an
expert in the management of lead chemotherapy prior to using chelation
agents. If unaware of a center with such expertise, PCPs should contact
their local or state lead poisoning prevention program, local poison
control center, or the Lead Poisoning Prevention Branch at CDC
(404-498-1420) for the names of accessible experts. A child with an EBLL
and signs or symptoms consistent with encephalopathy should be chelated in
a center capable of providing appropriate intensive care services!
Controversy
exists as to the appropriate level at which to initiate chelation therapy,
and which drugs are most appropriate. Succimer treatment of young children
with BLLs < 45 µg/dL lowered their BLLs
but failed to improve their neurodevelopmental test scores (37).
(See Chapter 5, "Developmental Assessment and Interventions.")
Chelation therapy with succimer is addressed in a document on
pharmaceutical agents in the treatment of lead poisoning (38).
If oral outpatient chelation therapy is undertaken, the case manager should ensure that caregivers adhere to the prescribed dosing schedule and should serve as the liaison between the medical community and the child’s caregiver. Treatment should occur in a lead-safe environment.
Measurement of BLLs is the main method of determining whether significant absorption of lead has occurred, how urgently intervention is needed, and how successful case management has been. When a child’s BLL does not fall within a reasonable amount of time, it is the responsibility of the case manager and other team members to determine the cause of failure. The rate of BLL decrease can depend on both the amount of lead in the child’s body and the duration of the BLL elevation. A course of chelation therapy with succimer results in a rapid fall in BLL after 1 week of treatment. However, BLLs of those treated rebound after treatment ends, and by approximately 7 weeks after an initial course of therapy, BLLs of treated patients may reach almost 75% of prechelation levels (39). CDC recommends rechecking children’s BLLs 7 to 21 days after completion of chelation therapy (40). A continuing increase in children’s BLLs above the rebound level during the follow-up period may indicate continuing or possibly increased exposure to lead and definitely indicates a need for further environmental investigation. Common causes of rising BLLs include failure to address hazards in the child’s environment, improper environmental lead abatement techniques, and continued use of imported pottery, cosmetics, or folk medicines that are contaminated with lead. However, medical conditions resulting in bed rest or similar immobilization (41), or in acidosis (42), can cause children’s BLLs to rise unexpectedly, or fail to fall.
Confirmation of BLL by Venous Sample
Any screening BLL above 10 µg/dL must be confirmed with a venous sample. The time frame for confirmation depends upon the initial BLL (Table 3.3). In general, the higher the screening BLL, the sooner the confirmatory test. However, if a child is less than 12 months old, or if there is reason to believe that the BLL is rising rapidly, an earlier diagnostic confirmation may be indicated.
Table 3.3. Recommended Schedule for Obtaining a
Confirmatory Venous Sample
Screening test result (µg/dL) |
Perform a confirmation test within: |
10-19 |
3 months |
20-44 |
1 week-1 montha |
45-59 |
48 hours |
60-69 |
24 hours |
> 70 |
Immediately as an emergency lab test |
aThe higher the BLL on the screening test, the more urgent the need for confirmatory testing.
Table adapted from: Screening Young Children for Lead Poisoning: Guidance for State and Local Public Health Officials. Atlanta: CDC; 1997.
Follow-Up Venous Blood Lead Testing
Medical management includes follow-up blood lead testing. Table 3.4 presents the suggested frequency of follow-up tests. This table is to be used as guidance. Case managers and PCPs should consider individual patient characteristics and caregiver capabilities and adjust the frequency of follow-up tests accordingly.
Table 3.4. Schedule for Follow-Up Blood Lead Testinga
Venous blood lead level (µg/dL) |
Early follow-up (first 2-4 tests after identification) |
Late follow-up (after BLL begins to decline) |
10-14 |
3 monthsb |
6-9 months |
15-19 |
1-3 monthsb |
3-6 months |
20-24 |
1-3 monthsb |
1-3 months |
25-44 |
2 weeks-1 month |
1 month |
> 45 |
As soon as possible |
Chelation with subsequent follow-up |
aSeasonal variation of BLLs exists and may be more apparent in colder climate areas. Greater exposure in the summer months may necessitate more frequent follow ups.
bSome
case managers or PCPs may choose to repeat blood lead tests on all new
patients within a month to ensure that their BLL level is not rising more
quickly than anticipated.
Managing a Child’s Nutrition
Although the effectiveness of nutritional interventions has not been established, the following recommendations are common sense and are appropriate advice for all children, including those with EBLLs:
Dietary information is discussed in detail in Chapter 4, "Nutritional Assessment and Interventions."
Educating Caregivers
Educating caregivers is an important part of case management. Caregivers need to understand EBLLs and the risks that an EBLL poses to their child, what they can do to eliminate their child’s exposure to lead, and the importance of follow-up. It is important to not overburden caregivers and to provide them with understandable information and manageable interventions. (See Chapter 6, "Educational Interventions for Caregivers," for a detailed discussion.)
Monitoring a Child’s Developmental Progress
Follow-up also requires attention to the behavioral sequelae of EBLLs. Neurodevelopmental monitoring should continue long after a case meets BLL closure criteria, as many deficits will not manifest themselves until after a child starts school. Because developmental history and testing at the time of an EBLL usually will not identify lead-caused problems, a child’s EBLL history should be part of his or her permanent medical record. A referral for testing of intellectual and behavioral performance, whether or not related to EBLLs, should be made if indicated. (See Chapter 5, "Developmental Assessment and Interventions," for details.) The PCP and case manager should be intimately involved with any educational and behavioral interventions, in consultation with developmental and behavioral experts.
Monitoring Caregiver Compliance with Follow-Up Measures
For many reasons, caregivers may have trouble adhering to follow-up measures. Case managers, PCPs, and other members of the case management team must be careful not to blame the caregivers but should continue to make them aware that follow-up is for the benefit of the child. Caregivers may have trouble appreciating the importance of follow-up for asymptomatic children. Many caregivers have problems with basic needs such as transportation, food, or paying monthly bills. Therefore, it is important to limit interventions to those most likely to benefit the child while being within the capabilities of the caregiver. Punitive interventions, such as referring children to protective services, should be done as a last resort, when all more constructive approaches have been exhausted. Members of the case management team should always remember that virtually all caregivers are doing the best they can for their children and should be assisted in their efforts.
Recommendations for Future Research
Figure 3.1. Lowest Reported Effect Levels of Inorganic Lead in Children
Source: Preventing Lead Poisoning in Young Children, Centers for Disease Control and Prevention; 1991.