ELEVATION OF ZINC PROTOPORPHYRIN LEVELS IN LEAD WORKERS WITH IRON-SUFFICIENT MICROCYTOSIS

Zinc protoporphyrin (ZPP) measurement is a required test under the Occ upational Safety and Health Administration's lead standard. However, t here is no mention of the influence of hemoglobinopathy on the ZPP tes t value. We undertook a retrospective laboratory review of 382 employe es at the Argonne National Laboratory who had been subjects in a lead surveillance program since 1982. A total of 321 samples were analyzed, after female subjects and samples with abnormally high bilirubin leve ls were excluded. A group with low mean red blood cell volume (MCV; le ss than 80.0 fL) was compared with a group with normal MCV (greater or equal to 80.0 fL). A statistically significant difference teas noted in ZPP (P < 0.007) and total bibirubin (P < 0.0003) values of two grou ps. There was no statistically significant difference noted in age, le ad levels, or iron levels between the two groups. Abnormally high ZPP levels may occur in individuals with hemoglobinopathies. Only a minor part of this elevation could be explained by the higher bilirubin leve ls.