The influence of menstrual blood loss and age on the isotopic composition of Cu, Fe and Zn in human whole blood

Since there is a significant difference in the isotopic composition of Cu and Fe in whole blood between men and women, it was hypothesized that menstruation and the associated Cu and Fe loss affect the isotopic composition of these metabolically relevant transition metals. To assess this hypothesis, whole blood from two groups of non-menstruating women was analyzed for its Cu, Fe and Zn isotopic composition using multi-collector ICP-mass spectrometry (MC-ICP-MS) and the results were compared to the values for a male and a female reference population. The first group of non-menstruating women consisted of women in their menopause, while the second group consisted of women that were not menstruating because of an intra-uterine device (IUD). Also the effect of age on the isotopic composition of Cu, Fe and Zn in whole blood was investigated. The Cu and Fe isotopic composition of whole blood indeed seems to be influenced by menstruation. Non-menstruating women show an isotopic signature indistinguishable from that of the male reference population. The results for both groups of non-menstruating women do not differ significantly from one another and there does not seem to be an "age effect" for these two elements. Also for the isotopic composition of Zn in whole blood, no age effect could be demonstrated. No influence of menstruation was found either. However, a significant difference in the Zn isotopic composition was found between women in their menopause and women with an IUD. Possibly, this can be explained by a hormonal effect on the isotopic signature of Zn. To assess the effect of menstruation on the isotopic composition of whole blood Cu, Fe and Zn, samples from two groups of non-menstruating women were analyzed using multi-collector ICP-MS and the results were compared to the values for a male and a female reference population.