title: Vitamin D in plasma: quantitation by a nonequilibrium ligand binding assay.
abstract: The concentration of vitamin D was determined in human and bovine plasma samples under various physiological and nonphysiological conditions using a nonequilibrium ligand binding assay. Prior to ligand binding analysis the vitamin D in the plasma organic extracts was purified using chromatographic procedures involving Lipidex-5000 and high performance liquid chromatography. The use of a nonequilibrium assay system greatly increased the sensitivity of our assay allowing for a minimum volume of the initial plasma sample. The vitamin D levels in plasma responded to increased sun exposure as well as to the intoxication with vitamin D3. Analysis of a plasma sample from a vitamin D-deficient patient revealed that lipid interference was not a factor in this ligand binding assay.
mesh_terms: D015650:24,25-Dihydroxyvitamin D 3; D000818:Animals; D001667:Binding, Competitive; D002112:Calcifediol; D002352:Carrier Proteins / Q000378:metabolism; D002417:Cattle; D002762:Cholecalciferol / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004100:Dihydroxycholecalciferols / Q000378:metabolism; D004872:Ergocalciferols / Q000378:metabolism; D006801:Humans; D006887:Hydroxycholecalciferols / Q000378:metabolism; D008832:Microchemistry / Q000379:methods; D014807:Vitamin D / Q000097:blood* / Q000378:metabolism / Q000633:toxicity; D014808:Vitamin D Deficiency / Q000097:blood; D014809:Vitamin D-Binding Protein
chemical_list: D002352:Carrier Proteins; D004100:Dihydroxycholecalciferols; D004872:Ergocalciferols; D006887:Hydroxycholecalciferols; D014809:Vitamin D-Binding Protein; D014807:Vitamin D; D002762:Cholecalciferol; D015650:24,25-Dihydroxyvitamin D 3; D002112:Calcifediol