Reference values for trace essential elements in the whole blood and serum samples of the adult Serbian population: significance of selenium deficiency.

This study was aimed to determine reference values (RVs) for the manganese (Mn), copper (Cu), zinc (Zn), and selenium (Se) in the whole blood (B) and serum (S) samples of the Serbian population. Blood specimens were collected from healthy persons (n = 295; women/men ratio = 149/146; mean age: 42 ± 2 years). The RVs were calculated as lower limit (LL) and upper limit (UL) of the 95% confidence interval (CI) and were expressed as percentiles (P) in the range from P2.5 to P97.5. The influences of sex, age, and smoking habits on element profiles were considered. It was found that the contents of B-Cu and S-Cu were higher in women, while the contents of B-Zn and S-Zn were higher in men. Both trace elements were significantly increased in a group of persons above 40 when compared to a younger persons (≤ 40 years). According to smoking habits, increased content was found only for S-Mn in the nonsmoker's group (p < 0.05). Comparing our results to the results reported in other population groups worldwide, the Serbian population had significantly reduced content of Se in both types of samples. This finding could highlight the deficiency of Se in the investigated Serbian population and could contribute to the better understanding of the molecular basis for the increased incidence of thyroid and other diseases in which selenium plays a key role.