Document GKXw672vY8M9ML41pG82JyQ3x

3-5IS7 We invite your reactions to any article in Patient Care Lead toxicity: Chelate at what level? PETER D. MAGNUS, MD, MPH, deputy director, child health, Los Angeles County Department of Health Ser vices; assistant clinical professor of pediatries, University of Southern California, Los Angeles County Medical School: I enjoyed the com prehensive article "Lead toxicity from suspicion to therapy" (May 15, 1976, page 80). However, I believe further elucidation is necessary. According to the chart on relative lead intoxication (page 86), a range of 30-49 /tg Pb/dl is considered minimally elevated. However, a lead level in this range is an exces sive burden that may manifest itself only in terms of subtle symptom atology in the early school years. Only the more obvious signs of frank lead poisoning are mentioned in the article; however, recent lit erature has been filled with concern over neuropsychological sequelae of low-level lead burdens (more than 30 /xg/dl) and the difficulty in quan tifying levels of future impairment in asymptomatic toddlers with symptomatology manifested in the early school years. These often subtle sequelae of low lead levels include minimal brain dysfunction, hyperkinesis, learning disabilities, and abnormalities of visual-motor functioning, behavior, and attention span.1'8 According to the schema of the article, children with blood lead levels of 30-50 fxgldl and high FEPs would merely receive surveillance lead determinations, assuming any iron-deficiency anemia and environ mental influences were being cor rected. A child is permitted to sta bilize at 40-45 (xg Pb/dl whole blood and remain at this level, perhaps until puberty! In our Los Angeles experience, this level may yield FEP values ranging from 110 to several hundred /xg/dl without iron deficiency. The big question is: If these lower levels of excessive lead burdens are affecting the enzymes in the developing RBCs in terms of heme precursors, what neurotoxic effects do they have? Children more than 5 years old may well have lead values of more than 30 /xg/dl, with FEP values less than 60 /xg/dl; the younger the child, however, the greater the elevation of FEP due to either a lead burden or iron defi ciency.9'10 I would be loath to manage a child of 1-5 years whose lead is 78 /xg/d1 and FEP is 185 /xg/dl whole blood as "moderately elevated." Accord ing to the article, "as long as the child is asymptomatic, remove the source of lead and check him every 2-3 months (once a month during the summer) until lead levels show a decline" and stabilize at about 4045 fig Pb/dl. I feel this child merits an initial five-day course of calcium EDTA, at about 50 mg/kg IM,11 and an eight-hour urine collection after the injection on days 1 and 5 of chelation to assess body (soft tissue) lead burden. Finally, I'fed that the caldum disodium edetate (Versenate) mobi lization test or "provocative test" need not be labeled a "sophisticated screening test" used only in "symp tomatic patients" and "done by re searchers in a hospital setting." The test can be very useful in an in- or outpatient setting' to determine t.hf amount of chelatable lead, and hence, the need for a full course of chelation therapy. A positive test does not necessarily mean that a child needs to be chelated, but it will give tile clinician a better idea of the body lead burden. Perhaps if the test is very positive (either >2 mg Pb/liter of urine, or twice as many fig of lead excreted per liter of urine than mg of ED'fA given) most clinicians working with children with plumbism would agree to chelate, even in children with mild-to-moderate blood lead; values. A provocative test would not be necessary prior to chelation if the blood lead level is greater than 60 /xg/dl on two successive oc casions, if print chips are seen on abdominal flat plates, or if lead lines are present on long bone films. By chelation, I mean use of EDTA alone on an ambulatory basis (com bined, of course, with environ mental and nutritional ameliora tion.) Only with extremely elevated lead levels (s 70 /xg/dl), a symp tomatic child, or a horrendous envi ronment should hospitalization be mandatory. Thus, each case must be consid ered individually, regardless of classification, and chelation should only be performed after the need has been demonstrated. Health ed ucation for the parents, nutritional counseling, and environmental as sessment and correction---com bined, perhaps, with oral iron to reset the child's "picastat" and cor rect the iron deficiency--are often more important than the medical management of the burdened child. 1. Zarkowsky HS; The lead problem in children; Dic tum and polemic- Curr Prob Pediatr 6:1-47, Jul 76. 2. Bryce-Smith D, Waldron WA: Lead, behavior, and criminality. The Ecologist 4:367, Dec 74. 3. Recommendations for the prevention of lead poi soning in children. Committee on Toxicology, Assem bly of Life Sciences National Research Council; Na tional Academy of Sciences, jul 76. 4. David O, Clark J. Voeller K: Lead and hyperac tivity. Lancet 2:900-3, 1972. 5. Lansdown RG, Clayton BE, Graham PJ, et al: Blood-lead levels, behavior, and intelligence: A popu lation study. Lancet 1:538-41, 1974. 6. de la Burde B, Choate MS Jr: Early asymptomatic lead exposure and development at school age. J Pe diatr 87:638-42, 1975. 7. de la Burd4 B, Choate MS Jr; Does asymptomatic lead exposure in children have latent sequelae? J D-diatr 81:1088-91, 1972. continued DUP040008130