Metabolism of 1,25-Dihydroxyvitamin D3: Evidence for Side-Chain Oxidation

Rajiv Kumar, Deborah Harnden, Hector F. DeLuca

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62 Scopus citations


Approximately 7% of a 650-pmol dose of 25- hydroxy [26,27-14C] vitamin D3 and 25% of a 325-pmol dose of 1,25-dihydroxy[26,27-14C]vitamin D3 are metabolized to 14CO2 by vitamin D deficient rats. Nephrectomy prevents the metabolism of 25-hydroxy [26,27-14C] vitamin D3 to 14CO2 but not that of 1,25-dihydroxy [26,27-14C] vitamin D3. Less than 5% of the14C from 24,25-dihydroxy[26,27-14C]vitamin D3 is metabolized to14CO2. Feeding diets high in calcium and supplemented with vitamin D3 markedly diminishes the amount of14CO2 formed from 25-hydroxy[26,27-14C]vitamin D3 but not that from 1,25-dihydroxy[26,27-14C]vitamin D3. These results provide strong evidence that only 1-hydroxylated vitamin D compounds and especially 1,25-dihydroxyvitamin D3 undergo side-chain oxidation and cleavage to yield an unknown metabolite and CO2.

Original languageEnglish (US)
Pages (from-to)2420-2423
Number of pages4
Issue number11
StatePublished - Jun 1 1976

ASJC Scopus subject areas

  • Biochemistry


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