Markowitz M E, Rosen J F, Bijur P E
Department of Pediatrics, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, New York 10467.
J Pediatr. 1990 Mar;116(3):360-4. doi: 10.1016/s0022-3476(05)82821-5.
The effect of iron status on calcium disodium edetate (CaNa2EDTA)-induced lead diuresis was examined in 112 children with moderate lead intoxication. Patients whose blood lead levels were between 25 and 55 micrograms/dl and who had erythrocyte protoporphyrin concentrations greater than or equal to 35 micrograms/dl underwent provocative testing to determine the need for a full course of chelation therapy. A blood sample for lead, erythrocyte protoporphyrin, and serum ferritin determinations was obtained immediately before the intramuscular administration of CaNa2EDTA, 500 mg/m2. Determination of urinary lead level was based on an 8-hour urine collection. Blood lead and ferritin levels were significantly correlated with urinary lead excretion: r = 0.542 and 0.298, respectively, p less than 0.01 for both. Multiple regression models were tested to assess the independent effects of the variables. With blood lead level controlled, ferritin remained significantly associated with urinary lead excretion; for every 1 ng/ml increase in ferritin, urinary lead increased by 2.4 micrograms. This small effect of ferritin on urinary lead was illustrated in a discriminant analysis. Using blood lead level by itself as the independent variable resulted in a 76% correct assignment of provocative test outcomes. Knowing the ferritin level improved this assignment accuracy by only 3%. We conclude that the iron status, as measured by serum ferritin, of children with moderate lead intoxication, has a small but significant effect on CaNa2EDTA-induced lead diuresis. This effect may influence the interpretation of borderline provocative test outcomes. Although chelation therapy should not be withheld pending treatment of iron deficiency, lead stores should be reassessed after iron repletion.
在112名中度铅中毒儿童中研究了铁状态对依地酸钙钠（CaNa2EDTA）诱导的铅利尿作用的影响。血铅水平在25至55微克/分升之间且红细胞原卟啉浓度大于或等于35微克/分升的患者接受激发试验，以确定是否需要进行全程螯合治疗。在肌肉注射500mg/m2 CaNa2EDTA之前，立即采集一份用于测定铅、红细胞原卟啉和血清铁蛋白的血样。尿铅水平的测定基于8小时尿液收集。血铅和铁蛋白水平与尿铅排泄显著相关：相关系数r分别为0.542和0.298，两者p均小于0.01。测试了多元回归模型以评估各变量的独立作用。在控制血铅水平后，铁蛋白仍与尿铅排泄显著相关；铁蛋白每增加1ng/ml，尿铅增加2.4微克。铁蛋白对尿铅的这种微小作用在判别分析中得到了体现。仅将血铅水平作为自变量时，激发试验结果的正确分配率为76%。了解铁蛋白水平仅将这种分配准确性提高了3%。我们得出结论，中度铅中毒儿童的铁状态（以血清铁蛋白衡量）对CaNa2EDTA诱导的铅利尿作用有微小但显著的影响。这种影响可能会影响对临界激发试验结果的解释。虽然不应在缺铁治疗之前停止螯合治疗，但在补铁后应重新评估铅储存情况。
