title: Lead toxicity and heme biosynthesis.
abstract: Lead intoxication results in a disturbance of heme biosynthesis, its degree depending on the severity and duration of exposure to lead. A mild secondary, sideroblastic anemia is common; basophilic stippling may occur, especially in severe lead poisoning. Increased excretion in the urine of delta-aminolevulinic acid and coproporphyrin III may occur; porphobilinogen excretion is not usually increased. Delta-aminolevulinate dehydratase, coproporphyrin oxidase, and ferrochelatase activities are reduced; delta-aminolevulinate synthetase activity is increased. Erythrocyte protoporphyrin (FEP and ZPP) is increased. Recent knowledge of the heme biosynthetic enzymes is reviewed and the significance of FEP and ZPP discussed. A brief history is given of the relationship of lead toxicity to the porphyrins.
mesh_terms: D000624:5-Aminolevulinate Synthetase / Q000378:metabolism; D000622:Aminolevulinic Acid / Q000652:urine; D055598:Chemical Phenomena; D002621:Chemistry; D003304:Coproporphyrinogen Oxidase / Q000378:metabolism; D003306:Coproporphyrins / Q000652:urine; D004912:Erythrocytes / Q000378:metabolism; D005294:Ferrochelatase / Q000378:metabolism; D006418:Heme / Q000096:biosynthesis*; D006801:Humans; D007855:Lead Poisoning / Q000378:metabolism*; D000623:Porphobilinogen Synthase / Q000378:metabolism; D011524:Protoporphyrins / Q000097:blood
chemical_list: D003306:Coproporphyrins; D011524:Protoporphyrins; D006418:Heme; D000622:Aminolevulinic Acid; D003304:Coproporphyrinogen Oxidase; D000624:5-Aminolevulinate Synthetase; D000623:Porphobilinogen Synthase; D005294:Ferrochelatase