(24S)-24,25-Dihydroxyvitamin D3 ((24S)-24,25-Dihydroxycholecalciferol) is a isomer of 24,25-dihydroxyvitamin D3. Vitamin D is metabolized in the liver to 25-hydroxyvitamin D3, and in the kidney to 1,25-dihydroxyvitamin D3 and 24,25-dihydroxyvitamin D3.