By means of the determination of selenium in blood it can be found out if the selenium supply is sufficient. The measurement of the selenium level can be realised from the serum ("aqueous part" of the blood) or from the whole blood. In contrast to the serum value, from which only the current supply with selenium is measured, the whole blood value reflects the long-term supply. Thus, the serum selenium value can be measured already as "normal" whereas the whole blood value still signalises a deficiency. The realisation of the selenium measurement is done by special laboratories as a matter of routine.
In the international comparison, rather lower selenium levels are measured in Germany :
53-79 µg selenium per litre (whole blood)
Recommendation for ideal selenium levels in blood [1,2,3]:
101-139 µg selenium per litre (serum)
121-168 µg selenium per litre (whole blood)