The ratio of erythrocyte zinc-protoporphyrin to protoporphyrin IX in disease and its significance in the mechanism of lead toxicity on haem synthesis.
Protoporphyrin and zinc-protoporphyrin were measured in the erythrocytes of normal subjects, workers exposed to lead and patients with iron deficiency and erythropoietic protoporphyria (EPP). Results showed significantly higher levels of zinc-protoporphyrin in the lead-exposed workers (P < 0.0001), patients with iron deficiency (P < 0.0001) and EPP patients (P < 0.001) compared with normal subjects. The lead-exposed workers showed the highest levels of zinc-protoporphyrin, which were significantly greater than both the iron-deficient and EPP patients (P < 0.0001). They also showed a higher ratio of zinc-protoporphyrin to free protoporphyrin compared with normal subjects (P < 0.0001) but no significant difference in this ratio was found when compared with iron-deficient patients (P = 0.1). These results are discussed in light of the controversy concerning the mechanism of formation of zinc-protoporphyrin in lead exposure.
Nelson
J C
JC
Department of Chemical Pathology and Immunology, United Leeds Teaching Hospitals (NHS) Trust, Leeds General Infirmary, UK.
Westwood
M
M
Allen
K R
KR
Newton
K E
KE
Barth
J H
JH
D000328:Adult; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D006418:Heme / Q000096:biosynthesis*; D006801:Humans; D007855:Lead Poisoning / Q000097:blood*; D008297:Male; D011524:Protoporphyrins / Q000097:blood*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D011524:Protoporphyrins; C017803:zinc protoporphyrin; D006418:Heme