Morgan J M, Burch H B
J Lab Clin Med. 1975 May;85(5):746-55.
The measurement of erythrocyte delta-aminolevulinic acid dehydratase (ALA-D) activity has been found to be a useful guide to lead exposure for screening purposes. The pH of the test should be well-controlled for adequate clinical interpretation. False-normal tests are rare even with iron-deficiency anemia or macrocytosis. Recent transfusion and recent bleeding or hemolysis with reticulocytosis tend to invalidate the test. ALA-D activity above 600 International Units effectively excludes significant lead exposure and eliminates the need for further testing. ALA-D activity is maximally depressed at a red cell lead concentration of 200 mug per 100 ml. When activity is moderately depressed, interpretation is difficult and the urinary excretion of lead after the administration of a chelating agent is usually required to differentiate the degree and significance of lead exposure.
红细胞δ-氨基-γ-酮戊酸脱水酶（ALA-D）活性的测定已被发现是用于筛查目的的铅暴露的有用指标。为了进行充分的临床解读，测试的pH值应得到良好控制。即使存在缺铁性贫血或大细胞性贫血，假正常测试也很少见。近期输血以及近期出血或伴有网织红细胞增多的溶血往往会使测试无效。ALA-D活性高于600国际单位可有效排除显著的铅暴露，并无需进一步检测。当每100 ml红细胞铅浓度为200 μg时，ALA-D活性被最大程度抑制。当活性中度受抑制时，解读困难，通常需要在给予螯合剂后测定尿铅排泄量，以区分铅暴露的程度和意义。
