Den vigtigste funktion for 1, 25 dihydroxyvitamin D3 er at øge den intestinale absorption af både kalcium og fosfat såvel som at regulere serumkalcium, renal kalcium og fosfatudskillelsen, knogleopbygningen og knogleresorptionen.
The principal action of 1,25-dihydroxyvitamin D3 is to increase intestinal absorption of both calcium and phosphate as well as regulate serum calcium, renal calcium and phosphate excretion, bone formation and bone resorption.