[Re-assessment of indicators for screening lead poisoning].
OBJECTIVE
To determine the accuracy of the indicators for detecting lead poisoning.


METHODS
Blood and urine specimens in 157 workers exposed to lead were collected. Their blood levels of lead, free erythrocyte protoporphyrin (FEP), zinc protoporphyrin (ZPP), urine delta-aminolevulinic acid and activity of red cell pyrimidine 5'-nucleotidase were determined, with gold standards of blood lead levels of >or= 1.93 micromol/L and >or= 2.90 micromol/L. Accuracy assessment of the indicators mentioned above for detecting lead poisoning was based on the area under the receiver operative characteristic (AUC(ROC)) curve with a software specially for ROC curve analysis and software of Epi-Info, after determining the optimal cut-off points for the above mentioned indicators in detecting those with blood lead >or= 1.93 micromol/L and >or= 2.90 micromol/L. The sensitivity of screening in parallel for detecting those with blood lead >or= 1.93 micromol/L and >or= 2.90 micromol/L was calculated and compared.


RESULTS
For detecting those with blood lead level >or= 1.93 micromol/L, the area under ROC curve (AUC(ROC)) of above indicators was 0.978 for ZPP, 0.973 for red cell P5'N, 0.937 for FEP, 0.890 for urine delta-ALA (significantly different from that for ZPP with P < 0.05), and 0.845 for urine lead level (significantly different from that for ZPP with P < 0.05), respectively. For detecting those with blood lead level >or= 2.90 micromol/L, the area under ROC curve (AUC(ROC)) of above indicators was 0.975 for red cell P5'N, 0.954 for ZPP, 0.906 for FEP (significantly different from that for red cell P5'N with P < 0.05), 0.900 for urine delta-ALA (significantly different from that for red cell P5'N with P < 0.05), and 0.750 for urine lead level (significantly different from that for red cell P5'N with P < 0.05). Sensitivity of screening in parallel with ZPP and P5'N was significantly higher than that with urine levels of lead and delta-ALA.


CONCLUSIONS
Determinations of red cell P5'N and ZPP for detecting those with blood lead >or= 1.93 micromol/L and >or= 2.90 micromol/L are more accurate.
Lü
L
L
Shanghai Medical University, Shanghai, 200040.
Lin
G
G
Xu
M
M
Zou
H
H
Wang
Q
Q
D015720:5'-Nucleotidase / Q000097:blood; D000328:Adult; D000622:Aminolevulinic Acid / Q000652:urine; D005260:Female; D006801:Humans; D007854:Lead / Q000097:blood*; D007855:Lead Poisoning / Q000097:blood / Q000517:prevention & control*; D008297:Male; D008403:Mass Screening; D016273:Occupational Exposure / Q000009:adverse effects*; D011524:Protoporphyrins / Q000097:blood*; D012372:ROC Curve; D012680:Sensitivity and Specificity
D011524:Protoporphyrins; C017803:zinc protoporphyrin; D007854:Lead; D000622:Aminolevulinic Acid; D015720:5'-Nucleotidase