Back25(OH)-Vitamin D3/D2, LC-MS/MS

D-vitamins and calciferols arise from provitamins by the UV radiation of sunlight catalysed
splitting of the B ring of the steran backbone. The two most important D vitamins
are vitamin D3
and vitamin D2
. Contrary to vitamin D2
, which has to be added
via food, vitamin D3
can be produced in the liver.
In the skin formed or together with vitamin D2
by food ingested vitamin D3
is bound
to a vitamin D binding protein in the plasma, transported into the liver and hydroxylated
in position 25 to form 25-OH-D. More than 95% of 25-OH-D is 25-OH-D3
. 25-
OH-D2
is only detectable in patients with medication of vitamin D2
.