1,25-Dihydroxyvitamin D is not responsible for toxicity caused by vitamin D or 25-hydroxyvitamin D

► 1,25-Dihydroxyvitamin D is not responsible for vitamin D intoxication. ► 25-Hydroxyvitamin D is likely responsible for vitamin D3 intoxication. ► CYP27B1 deletion does not reduce or enhance vitamin D intoxication.