Determination of blood total, reduced, and oxidized glutathione in pediatric subjects.

hormone replacement therapy in postmenopausal women did not significantly alter ferritin concentrations. Whether this is because of different dosage schedules of the estrogens used or because of less blood loss in postmenopausal women has to be further evaluated. When subjects donated blood on a regular basis, a significantly lower ferritin concentration could be observed for men (x 5 23.242; P 5 0.0001) as well as for premenopausal women (not shown). This correlates well with the results of Punnonen and Rajamäki (23 ), who showed that 17% of Finnish women who frequently donated blood had completely lost their iron stores. Unlike the findings of Vernet and Doyen (18 ), who found increased sTfR concentrations in males who regularly donated blood, we found that blood donation did not affect sTfR concentrations. This may be caused by compensation of the chronic blood loss by mobilizing iron from storage pools. These findings suggest that serum sTfR concentrations will only be increased when erythropoiesis becomes deprived of iron, whereas a decrease in serum ferritin will reflect changes over a broad range of body iron stores. In premenopausal women, we found significantly higher sTfR concentrations compared with postmenopausal women (x 5 6.5076; P 5 0.0107), which is in contrast with the earlier findings of Allen et al. (11 ). In our opinion, this difference may be a result of the more rigid exclusion criteria or the low number of postmenopausal women involved in their study.