Zinc protoporphyrin in blood as a biological indicator of chronic lead intoxication.

Traditionally, the diagnosis of lead intoxication has relied upon blood lead and urine lead determinations. However, metabolic changes in the biosynthetic pathway of heme as well as damage in other organ systems may occur at blood lead levels hitherto regarded as "safe." Lead intoxication leads to elevated zinc protoporphyrin (ZPP) levels in the blood which can be measured quickly, inexpensively and conveniently on a drop of unprocessed whole blood by means of a dedicated front face fluorometer, called a hematofluorometer. In the present study, ZPP showed a strong correlation with the lead-in-blood level, as well as with signs and symptoms of lead-related disease. It is concluded that zinc protoporphyrin determination offers a preferred primary screening test for lead-exposed populations.