Vectical

Calcitriol is the active form of vitamin D, normally made in the kidney.[8][9] It is also known as 1,25-dihydroxycholecalciferol. It is a hormone which binds to and activates the vitamin D receptor in the nucleus of the cell, which then increases the expression of many genes.[10] Calcitriol increases blood calcium (Ca2+) mainly by increasing the uptake of calcium from the intestines.[7] It can be given as a medication for the tr... [wikipedia]