Why is hair used for elemental analysis, not blood?
Hair represents one of the most metabolically active tissues, thus it provides regular information of the organism’s metabolic activity. The level of elements content in hair corresponds with the level of these elements in inner tissues, however, their concentration is much higher than in blood or serum, which makes it easier to assay them. Blood or serum analysis does not reflect the current elements concentration in the organism due to the action of certain mechanisms that regulate their levels (homeostatic mechanisms). Excesses of elements in the organism are often undetectable in serum for the reason of their transfer from blood to tissues.