Selenium speciation in human serum of cystic fibrosis patients compared to serum from healthy persons.

A formerly developed Se speciation method was applied to human serum. Chomatographic performance was checked regularly by measuring control standards after four sample run, each, to ensure sufficient separation of the species and sensitivity of the method even after a considerable number of serum samples. Detection limits of investigated species were similar to those reported and showed values below 1 microg/L related to Se for each Se compound. Sera of cystic fibrosis (CF) patients were investigated in comparison to sera from healthy volunteers with respect to total selenium and Se species. Generally, CF sera showed lower values of total Se, Selenocystine (SeC), and cationic/neutral Se compounds compared to serum of healthy persons. No significant gender-specific differences were found. Total Se in sera of healthy persons was determined at 102+/-12 microg/L (n = 12 individuals, mean value from male and female, age 4-38 years), whereas CF patients showed 58+/-10 microg/L (n = 31 individuals, mean value from male and female, age 3-35 years). Se-cystine showed significant differences between the CF and healthy group with a lowered SeC value in sera of CF patients by -75% (mean ca. 26 microg/L in healthy sera compared to about 6.5 microg/L (mean) in CF sera). A similar situation is seen for neutral/cationic Se compounds, which partly may comprise of Se proteins. The lowered SeC values together with lowered cationic/neutral Se compounds (probably Se enzymes) point to a Se-depleted regulated pathway combined with a reduced capability of protective functions such as protection from peroxides.