[Sex difference in free erythrocyte protoporphyrin (FEP) level. I. Sex difference in FEP level in healthy rural residents].

FEP and other hematological parameters were measured in 157 healthy rural residents (98 females and 59 males). The mean FEP in females was higher than in males (p less than 0.05); mean +/- SD = 62.98 +/- 19.36 and 54.57 +/- 21.20 micrograms/dl.pcv, respectively, although both of the means were within normal limits. There was no significant sex difference in erythrocyte ALA-D activity. Whole blood lead (Pb-B) level in females showed a tendency to be lower than in males, but there was no significant sex difference in erythrocyte lead level. The mean value of hematocrit (Ht), hemoglobin (Hb) and iron in serum (Fe-S) were lower in females than in males (p less than 0.01). Serum GOT and GPT level tended to be lower in females than in males (0.05 less than p less than 0.1). There was hardly any significant relationship between Pb-B and each parameter of lead exposure, because the subjects in this study were only rural residents with no occupational lead exposure and with their Pb-B levels being extremely low. As for the parameters of anemia, Fe-S was positively correlated with Ht and Hb level and negatively correlated with FEP level. By sex, Fe-S was correlated with Ht and FEP level only in females. As for the possible reasons why FEP level in females in higher than in male, women tended to have iron-deficiency induced by blood loss due to menstruation, pregnancy, and difference in dietary pattern from males.