Evaluation of the erythrocyte protoporphyrin test as a screen for elevated blood lead levels.

To study the effect of lowering the definition of an elevated blood lead level on the performance of the erythrocyte protoporphyrin screening test and the number of children who would require follow-up, we collected laboratory data from a screening program. The estimated sensitivity of an erythrocyte protoporphyrin level greater than or equal to 35 micrograms/dl for identifying children with elevated blood lead levels was 73% when we used 1985 Centers for Disease Control guidelines (elevated blood lead level greater than or equal to 25 micrograms/dl). Eight percent of the tests showed positive results. When we redefined an elevated blood lead level as greater than or equal to 15 micrograms/dl, the sensitivity estimate was reduced to 37% and the number of positive test results increased fourfold.