Screening children exposed to lead: an assessment of the capillary blood lead fingerstick test.
We describe results of a 3-year study in which 499 paired venous and capillary blood specimens, collected by fingerstick on the same day, were analyzed for lead (BPb) and erythrocyte protoporphyrin (EP). False-positive rates (FPRs) and the proportion of false positives were calculated at four BPb thresholds. At the 100 microg/L threshold, the FPR for all data was 13%, but the proportion of false positives was only 5%. The log ratios of capillary-to-venous BPb data indicate that, with the exception of eight outliers, two subpopulations exist that follow a log-normal distribution. These two subpopulations, the "core" (n = 303) and "shifted" (n = 188) groups, on average generated a positive bias at 100 microg/L BPb of 8.6% and 30.3%, respectively. The log ratios of capillary-to-venous EP data followed a normal distribution, indicating that capillary EP is not statistically different from venous EP.
Parsons
P J
PJ
Wadsworth Center, New York State Department of Health, Albany 12201-0509, USA. patrick.parsons@wadsworth.org
Reilly
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AA
Esernio-Jenssen
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D002196:Capillaries; D002648:Child; D002675:Child, Preschool; D004781:Environmental Exposure; D004912:Erythrocytes / Q000737:chemistry; D005189:False Positive Reactions; D005260:Female; D005385:Fingers; D006801:Humans; D007223:Infant; D007854:Lead / Q000097:blood*; D007855:Lead Poisoning / Q000517:prevention & control*; D008297:Male; D008403:Mass Screening; D011524:Protoporphyrins / Q000097:blood; D013054:Spectrophotometry, Atomic; D014680:Veins
D011524:Protoporphyrins; D007854:Lead