25-Hydroxyvitamin D3: evidence of an enterohepatic circulation in man.
Within 24 hr after intravenous administration of isotopic 25-hydroxyvitamin D3 to three normal adults for kinetic studies, one-third of the radioactivity was secreted into the lumen of the duodenum, probably with the bile. The subsequent intestinal reabsorption of over 85% of secreted radioactivity suggests that this major metabolite of vitamin D has a hitherto unrecognized enterohepatic circulation. Our observation of a dynamic hepatic secretion and intestinal reabsorption of radioactivity administered as 3H-labeled 25-hydroxyvitamin D3 to vitamin D-replete man is indicative of an enterohepatic circulation that may be of physiologic importance. It is conceivable that interruption in the recycling of 25-OH-D3 may be an important mechanism of acquired deficiency of vitamin D in gastrointestinal disease.
D000328:Adult; D004386:Duodenum; D005243:Feces / Q000032:analysis; D005260:Female; D006801:Humans; D006887:Hydroxycholecalciferols / Q000097:blood / Q000378:metabolism* / Q000652:urine; D001239:Inhalation; D007275:Injections, Intravenous; D008099:Liver / Q000378:metabolism*; D008102:Liver Circulation; D008297:Male; D014316:Tritium
D006887:Hydroxycholecalciferols; D014316:Tritium