The authors determined the metabolic clearance and production rates of 24,25-dihydroxyvitamin D3 in four normal healthy adults. They also examined the excretion of radioactivity in stool, urine, and bile after the intravenous administration of 24,25-[3H]dihydroxyvitamin D3 to human subjects. 24,25-Dihydroxyvitamin D3 is rapidly cleared from the plasma with a half-life of ~ 390 ± 25 min (mean ± SE). The metabolic clearance rate of 24,25-dihydroxyvitamin D3 was 9.2 ± 1.5 liters/day with a production rate of 26.4 ± 7.2 μg/day (mean ± SE). Within 1 day 13.0 ± 4.2% (mean ± SE) of the administered dose had appeared in the stool: by day 7, 48.8 ± 2.7% of the dose had appeared in the feces. Within 24 hr, 6.4 ± 0.8% of the administered dose appeared in the urine; 7.4 ± 1.8% of the dose had appeared in the urine within 2 days. The biliary excretion of 24,25-dihydroxyvitamin D3 was studied in two subjects. By 8 h, 15.3 ± 1.3% of the administered dose had appeared in the bile. The metabolites present in bile, feces, and urine were much more polar than 24,25-dihydroxyvitamin D3. These results demonstrate that 24,25-dihydroxyvitamin D3 is rapidly cleared from plasma and is excreted in the feces (probably via the bile) and urine of normal human subjects.
|Original language||English (US)|
|Journal||American Journal of Physiology - Endocrinology and Metabolism|
|State||Published - Jan 1 1982|
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Physiology (medical)