Iron status influences trace element levels in human blood and serum.

Food is the main source of trace elements for the general population. The gastrointestinal absorption of certain trace elements, e.g., cadmium, is strongly influenced by iron (Fe) status. This factor may also be relevant for the bioavailability of other trace elements. Therefore, we investigated relationships between Fe status indicators and trace element concentrations in blood and serum of 234 boys and girls at ages 15 and 17 years. Fe status was measured using serum ferritin (S-Ft), soluble transferrin receptor in serum (sTfR), and the ratio sTfR/S-Ft. The trace elements we investigated were, in blood, cadmium, cobalt, copper, zinc, selenium, rubidium, mercury, and lead, and, in serum, cobalt, copper, zinc, selenium, rubidium, tungsten, mercury, and lead. We found inverse correlations between Fe status and blood cadmium, blood or serum cobalt, or blood copper. There were positive correlations between Fe status and mercury concentrations. Selenium was positively correlated with sTfR. The relationships between Fe status and lead were equivocal. There were fewer correlations for serum than for blood, but the inverse relationships between Fe status and cobalt were equally strong in serum and blood. We found only occasional, and perhaps spurious, correlations with zinc, rubidium, and tungsten. In conclusion, previous indications that cadmium, cobalt, and copper are absorbed by transport mechanisms similar to that of Fe are supported by this study. Strong positive correlations between Fe status and mercury concentrations remain to be explained.