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Dosage of aspirin
Volume 97 Number 1
Editorial correspondence
Erythrocyte protoporphyrin in sickle cell disease
2.
To the Editor The report by Tigner-Weekes and associates on lead screening in sickle cell disease' indicates that erythrocyte protoporphyrin (EP) is often elevated ( > 50 ~g]dl whole blood) in children with sickle cell disease (SCD) without increased lead burden or iron deficiency. Of 13 patients with SCD who were studied with elevated EP, two were found to have evidence of iron deficiency and one was found to have lead overburden, which subjects 77% of these patients to be classified inappropriately based on the risk classification of lead poisoning by the Center for Disease ControF (high false positive rate). Even though the use.of EP as a screening tool has an unusually high false positive rate in children with SCD compared with non-SCD children, the risk as well as the need for case finding tbr either iron deficiency or lead poisoning is still necessary. At the outpatient clinic of Children's Health Center of Minneapolis, a recent routine EP screen using a Hematoflorometer found three children with SCD and elevated EP values. Upon further study all had evidence of iron deficiency (Fe/total iron-binding capacity < 16%, ferritin < 15 ng) and none had evidence of lead overburden (Pb < 30 big). Viehinsky et aP reported recently on the high rate (not specified) of EP elevation by extraction method in children with SCD and found 12 of 31 SCD children studied had evidence of iron deficiency, based on low transferrin saturation (15%) and/or low ferritin ( < 25 ~g). Of those with both low saturation and ferritin, only five responded to iron therapy. It may be reasonable tO regard low EP value in children with SCD as helpful in ruling out iron deficiency an d lead poisoning, whereas an elevated EP value deserves further work-up. The authors point out that high EP measurement in SCD may be related to a high level of "free" form of EP associated with reticulocytosis. This may imply that the free form of EP in SCD causes the elevated total EP (both free and complex form) which resulted in the high false positive rate for detecting lead poisoning and iron deficiency. Measurement of the zinc complex part of EP in SCD children may better reflect the metabolic consequence of lead burden or iron deficiency. Recently in our institution Schwartz et al 4 developed a quantitative method to measure both the free and complex form of EP, hopefully soon providing the necessary test for the above Observation and speculation. Ray Yip, M.D. Department of Pediatrics University of Minnesota and Children's Health Center of Minneapolis 2525 Chicago Ave. So. Minneapolis, M N 55404
4.
REFERENCES
1. Tigner-Weekes L, Pegelow C, Lee S, and Powars D: Lead screening in sickle disease, J PEDIATR 95:738, 1979.
3.
16 3
Center for Disease Control: Preventing lead poisoning in young children, J PEmATR 93:709, 1978. Vichinsky E, Kleman K, Davis JR, and Lubin B: The diagnosis of iron deficiency anemia in sickle cell disease, Blood 5(Suppl 1):47a, 1979. Schwartz S, Stephenson B, Sarkar H, et al: Quantitative assay of erythrocyte "Free" and zinc-protoporphyrin, clinical and genetic studies, lnt J Biol (in press).
Reply To the Editor: We elected to use the extraction ethyl acetate acetic acid HC1 method to measure free erythrocyte protoporphyrin (EP). Children with sickle cell anemia frequently have elevated serum bilirubin levels. Bilirubin is particularly notable for causing spuriously high E P measurements with the use of automated screening equipment (Hematofiuorimeter). 1 We wish to emphasize that EP elevations identified in the SS child can suggest the diagnosis of lead burden, iron deficiency, hyperbilirubinemia, or the physiologic elevations of "free" protoporphyrin IX seen with reticulocytosis in a young red cell population, or none of the above! Darleen Powars, M.D. University of Southern California School of Medicine Department of Medicine Los Angeles, CA 90033 REFERENCE
1.
Buhrmann E: The influence of plasma bilirubin on zinc protoporphyrin measurement by a hematofluorimeter, J Lab Clin Med 91:710, 1978.
Dosage of aspirin To the Editor." Dr. Done's recent recommendation on a revised aspirin dosage schedule will be extremely helpful to practicing pediatricians. ~ One question: In Fig. 4, why wasn't the dosage recommendation for age 12 seven of the 81 mg tablets rather than eight? The eight tablets give a 17 mg/kg dose which is above the author's recommended dosage range of 10 to 15. Also, the dosage suddenly jumps from six to eight tablets with seven tablets not being suggested for any age. Barton D. Schmitt, M.D. Department of Pediatrics University of Colorado Medical Center 4200 E. Ninth A re. Denver, CO 80262 REFERENCE
1.
Done AK, Yaffe SJ, and Clayton JM: Aspirin dosage for infants and children, J PEDIATR 95:617, 1979.
Editorial correspondence
Erythrocyte protoporphyrin in sickle cell disease
2.
To the Editor The report by Tigner-Weekes and associates on lead screening in sickle cell disease' indicates that erythrocyte protoporphyrin (EP) is often elevated ( > 50 ~g]dl whole blood) in children with sickle cell disease (SCD) without increased lead burden or iron deficiency. Of 13 patients with SCD who were studied with elevated EP, two were found to have evidence of iron deficiency and one was found to have lead overburden, which subjects 77% of these patients to be classified inappropriately based on the risk classification of lead poisoning by the Center for Disease ControF (high false positive rate). Even though the use.of EP as a screening tool has an unusually high false positive rate in children with SCD compared with non-SCD children, the risk as well as the need for case finding tbr either iron deficiency or lead poisoning is still necessary. At the outpatient clinic of Children's Health Center of Minneapolis, a recent routine EP screen using a Hematoflorometer found three children with SCD and elevated EP values. Upon further study all had evidence of iron deficiency (Fe/total iron-binding capacity < 16%, ferritin < 15 ng) and none had evidence of lead overburden (Pb < 30 big). Viehinsky et aP reported recently on the high rate (not specified) of EP elevation by extraction method in children with SCD and found 12 of 31 SCD children studied had evidence of iron deficiency, based on low transferrin saturation (15%) and/or low ferritin ( < 25 ~g). Of those with both low saturation and ferritin, only five responded to iron therapy. It may be reasonable tO regard low EP value in children with SCD as helpful in ruling out iron deficiency an d lead poisoning, whereas an elevated EP value deserves further work-up. The authors point out that high EP measurement in SCD may be related to a high level of "free" form of EP associated with reticulocytosis. This may imply that the free form of EP in SCD causes the elevated total EP (both free and complex form) which resulted in the high false positive rate for detecting lead poisoning and iron deficiency. Measurement of the zinc complex part of EP in SCD children may better reflect the metabolic consequence of lead burden or iron deficiency. Recently in our institution Schwartz et al 4 developed a quantitative method to measure both the free and complex form of EP, hopefully soon providing the necessary test for the above Observation and speculation. Ray Yip, M.D. Department of Pediatrics University of Minnesota and Children's Health Center of Minneapolis 2525 Chicago Ave. So. Minneapolis, M N 55404
4.
REFERENCES
1. Tigner-Weekes L, Pegelow C, Lee S, and Powars D: Lead screening in sickle disease, J PEDIATR 95:738, 1979.
3.
16 3
Center for Disease Control: Preventing lead poisoning in young children, J PEmATR 93:709, 1978. Vichinsky E, Kleman K, Davis JR, and Lubin B: The diagnosis of iron deficiency anemia in sickle cell disease, Blood 5(Suppl 1):47a, 1979. Schwartz S, Stephenson B, Sarkar H, et al: Quantitative assay of erythrocyte "Free" and zinc-protoporphyrin, clinical and genetic studies, lnt J Biol (in press).
Reply To the Editor: We elected to use the extraction ethyl acetate acetic acid HC1 method to measure free erythrocyte protoporphyrin (EP). Children with sickle cell anemia frequently have elevated serum bilirubin levels. Bilirubin is particularly notable for causing spuriously high E P measurements with the use of automated screening equipment (Hematofiuorimeter). 1 We wish to emphasize that EP elevations identified in the SS child can suggest the diagnosis of lead burden, iron deficiency, hyperbilirubinemia, or the physiologic elevations of "free" protoporphyrin IX seen with reticulocytosis in a young red cell population, or none of the above! Darleen Powars, M.D. University of Southern California School of Medicine Department of Medicine Los Angeles, CA 90033 REFERENCE
1.
Buhrmann E: The influence of plasma bilirubin on zinc protoporphyrin measurement by a hematofluorimeter, J Lab Clin Med 91:710, 1978.
Dosage of aspirin To the Editor." Dr. Done's recent recommendation on a revised aspirin dosage schedule will be extremely helpful to practicing pediatricians. ~ One question: In Fig. 4, why wasn't the dosage recommendation for age 12 seven of the 81 mg tablets rather than eight? The eight tablets give a 17 mg/kg dose which is above the author's recommended dosage range of 10 to 15. Also, the dosage suddenly jumps from six to eight tablets with seven tablets not being suggested for any age. Barton D. Schmitt, M.D. Department of Pediatrics University of Colorado Medical Center 4200 E. Ninth A re. Denver, CO 80262 REFERENCE
1.
Done AK, Yaffe SJ, and Clayton JM: Aspirin dosage for infants and children, J PEDIATR 95:617, 1979.