Disease relevance of Calcifediol

• Receptor content of rat breast tumor was investigated using an hydroxylapatite assay by incubating tumor extracts with a saturating concentration of 1,25-(OH)2-[3H]D3, plus unlabeled 25OHD3 to eliminate binding of the hormone to the 5-6 S species [1].
• In the mothers' plasma, the levels of 25-hydroxycholecalciferol (25OHD) and 1,25-dihydroxycholecalciferol (1,25(OH)2 D) were not different from control levels on day 18, but on day 21, 25OHD had increased, 1,25 (OH)2 D had diminished, and significant hypercalcemia was noted (10.1 +/- 0.27 mg/dl vs. 9.47 +/- 0.19 mg/dl, mean +/- SD) [2].
• The patient also had vitamin D-deficient osteomalacia that was confirmed by a low serum level of 25-hydroxyvitamin D3 (25OHD3) and by bone histomorphometry [3].
• This coexisting condition was caused by the long-term increase in conversion of 25OHD3 to 1,25(OH)2D3 from hyperparathyroidism in a patient with low stores of vitamin D (which were ascribed to aging, liver dysfunction in hyperthyroidism, a vegetarian diet, deprivation of sunlight, and avoidance of dairy products) [3].

High impact information on Calcifediol

• The ratio of total 25OHD3 and 1,25(OH)2D3 to plasma DBP, rather than total circulating vitamin D metabolites, may provide a more useful index of biological activity [4].
• This plasma binding protein revealed low affinity for 25OHD3, did not bind G-actin, and had a sedimentation coefficient of 3.4S [5].
• However, the serum 25-hydroxyvitamin D3 (25OHD3) and 24R,25-dihydroxyvitamin D3 (24R,25(OH)2D3) levels were significantly lower in the osteomalacic than in the non-osteomalacic marmosets [6].
• All Asian women who had high PTH values also had a very low serum 25-hydroxycholecalciferol level (25OHD) [7].
• Also, 25OHD3 and 1,25OH2D3 levels were significantly lower in preterm infants fed a taurine-free formula than in infants fed a taurine-enriched formula or human milk [8].

Anatomical context of Calcifediol

• Taurine, total bile acids, glyco-(GBA) and tauro-(TBA) conjugated bile acids, 25-hydroxyvitamin D3 (25OHD3) and 1,25-dihydroxyvitamin D3 (1,25OH2D3) were determined in all infants at birth in blood cord and at one and three months of life [8].

Analytical, diagnostic and therapeutic context of Calcifediol

• Renal 25OHD3 metabolism was measured in vitro by incubating renal cortical slices with tritiated 25OHD3 and quantifying tritiated metabolites by high pressure liquid chromatography [9].

References