Fluorometric assay of erythrocyte protoporphyrin: simple screening test for lead poisoning and iron deficiency.

Erythrocyte protoporphyrin levels are high in lead poisoning, iron deficiency and erythropoietic porphyria. On-site fluorometric assay was used to screen for raised blood levels in three groups of children in one city: 166 who were severely mentally retarded and lived in an institution, 88 who were moderately to severely mentally retarded and attending special schools but lived at home, and 128 who were of normal intelligence and attended a regular school. High erythrocyte protoporphyrin levels (40 micrograms/dl [0.7 mumol/l] or greater) were found in 14 of the children, each of whom was tested for further evidence of lead poisoning and iron deficiency. The two children found to have high blood lead levels (above 30 micrograms/dl [1.5 mumol/l]) were both living in the institution, were ambulatory and had pica. Of the other 12 children 8 had evidence of iron deficiency, though in 4 the probability of a true deficiency was low. The fluorometric assay of erythrocyte protoporphyrin may prove to be a simple method of screening for lead poisoning and iron deficiency.