See also Screening for Lead Poisoning

FEP can be abnormally high in Fe deficiency (even before any decrease in Hb or HCT occurs), so if you get an FEP that's high followed by a lead level that's ok, check a ferritin level (will be decreased in Fe deficiency) or just do a trial of supplementary FeSO4

(Sources include Core Content Review in Family Medicine, 2012)