Competitive protein-binding radioassay of 24,25-dihydroxyvitamin D in sera from normal and anephric subjects

Impaired 24,25-Dihydroxyvitamin D Production in Anephric Human and Pig

“…plasma. This result is in contrast to those in previous reports (7)(8)(9), in which detectable plasma 24,25-(OH)2D in anephric human plasma samples are described. Although none of the eight anephric patients in the present report had detectable plasma 24,25-(OH)2D3, two anephric patients (A-5 and A-7) had very low but detectable 24,25-(OH)2D2.…”

“…We have conifirmeed eairlier findinigs (10) that 24,25-(OH)2D is very low to nondetectable in anephric humans consuming normal dietary levels of vitamin D. This result conflicts with results in previous work (7)(8)(9). From our results, it is apparent that the other purification methods (7-9) for 24,25-(OH)2D determination do not adequately resolve material that will compete in the competitive protein-binding assay.…”

“…The normal human volunteers had plasma 24,25-(OH)2D concentrations of 2.8±0.7 ng/ml. Chronically dialyzed anephric and normal pigs were given intramuscular injections of massive amounts (5 x 106 IU) of vitamin D3 immediately after surgery (day 0) and again on day 7. In anephric pigs, plasma 25-OHD3 progressively rose from 12±4 nglml on day 0 to 705±62 ng/ml on day 10.…”

Age and seasonal variations in the serum levels of 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D in normal humans.

“…reported by several investigators (Taylor et al, 1976;Haddad et al, 1977;Graham et al, 1977;Kremer and Guillemant, 1978), but the reported ratio values are variable, ranging from5to 57%. The difference appears mainly due to differences in the degree of purification of the24, 25-(OH)2-D fraction.…”

23, 25, 26-trihydroxycholecalciferol. A 25-hydroxycholecalciferol-26,23-lactone precursor

“…One of these has been positively identified as 23,25,26-trihydroxycholecalciferol by u.v.-absorbance analysis, mass spectrometry and chemical formation of derivatives. 23,25,26-Trihydroxycholecalciferol produces when incubated in chick kidney homogenates.The major circulating metabolite of cholecalciferol is 25(OH)D3 (Hadded et al, 1977; Horst et aL, 198 la,b). 25(OH)D3-lactone is a significant 25(OH)D3 metabolite in animals receiving large doses of cholecalciferol (Wichmann et al, 1979;Horst, 1979).…”